Quick recall · 222 cards
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PYQ · 2022
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Which of the following statements about Ohm's Law is correct?
A. V is proportional to I
B. R varies with temperature
C. Applies only to metals
D. Current is inversely proportional to V
A · V is proportional to I
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For the parallel circuit with resistors 250 Ω, 300 Ω, and 175 Ω connected across 28 V, calculate the total current I.
B · 0.576 A
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An E.M.F. can be induced by _________
D · All of the mentioned
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What happens to the current in a coil while accelerating a magnet inside it?
C · It first increases and then decreases
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The total number of magnetic field lines passing through an area is termed as?
B · Magnetic flux
PYQ · 2023
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In electromagnetic induction, the energy is supplied to the circuit and a part of this supplied energy is spent to meet ____.
D · I²R loss
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In case of Inductive circuit, Frequency is ___________ Proportional to the inductance (L) or inductive reactance (XL).
B · Inversely
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Find the power factor of the circuit if R = 5 Ω, X_L = 12 Ω, frequency = 60 Hz.
C · 0.86 lagging
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Electric power in a Three Phase Circuit = _________.
C · Both 1 & 2
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For a star connected three phase AC circuit ________ ?
C · Sum of line voltages is zero
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A 120 V (per phase, rms) three-phase system has a balanced load consisting of three 10 Ω resistances. What total power is dissipated if the connection is a wye configuration?
D · 4320 W
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What is the power factor in a pure resistive AC circuit?
C · 1
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What happens to the overall power factor of a power system when an overexcited synchronous motor is connected in parallel with an induction motor load?
B · Overall power factor improves
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In a transformer, if the secondary coil has fewer turns than the primary coil, it is called:
B · B. Step-down transformer
When secondary turns N_s < primary turns N_p, voltage decreases (V_s < V_p), making it a step-down transformer. Option B matches this definition.
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A transformer works on:
B · B. AC supply only
Transformers operate via electromagnetic induction, requiring changing magnetic flux from AC supply. DC produces steady flux, so no induction. Option B is correct.
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The terminal potential difference of a cell of emf 2V and internal resistance 0.1Ω when supplying a current of 5A will be:
A · 1.5V
The terminal voltage V = E - Ir, where E is emf = 2V, I = 5A, r = 0.1Ω. Voltage drop Ir = 5 × 0.1 = 0.5V. Thus V = 2 - 0.5 = 1.5V. This matches option A.
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Which of the following is the correct charging method for Li-ion batteries?
C · Constant current followed by constant voltage
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What is the primary purpose of earthing electrical systems?
A · To maintain the potential of any part of the system at a defined value with respect to earth
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What is the role of earthing in relation to apparatus normally 'dead'?
B · To prevent them from reaching a dangerous potential
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Which statement is true about earthing systems?
B · They maintain the potential of the system with respect to earth
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What is the primary purpose of grounding in LV electrical installations?
C · C) Personnel safety and equipment protection
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What should be the minimum separation between two earth pits to avoid mutual interference?
B · B) Twice the length of the electrode
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The size of earth wire is determined by:
D · D) Both (A) and (C)
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Earth wire or ground wire is made of:
D · D) Galvanized steel
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Generally grounding is provided for:
C · C) Both (A) and (B)
Grounding protects both personnel from electric shock and equipment from damage due to fault currents or lightning. It ensures fault currents flow to earth, operating protective devices quickly.
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What does Ohm's Law state regarding the relationship between voltage (V), current (I), and resistance (R)?
C · Voltage is directly proportional to current and resistance
Ohm's Law states that \( V = IR \), meaning voltage is directly proportional to both current and resistance.
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Which of the following is a limitation of Ohm's Law?
B · It holds true only for linear and ohmic materials
Ohm's Law applies only to ohmic materials where resistance remains constant regardless of voltage and current.
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If the temperature of a metallic conductor increases, what happens to the validity of Ohm's Law?
B · Ohm's Law no longer holds because resistance changes
Resistance of metals changes with temperature, so Ohm's Law does not hold strictly at varying temperatures.
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Refer to the diagram below showing a resistor of \( 10 \, \Omega \) connected across a 5 V battery. Calculate the current flowing through the resistor using Ohm's Law.
A · \( 0.5\, A \)
Using \( I = \frac{V}{R} = \frac{5}{10} = 0.5\, A \).
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A resistor of \( 20\, \Omega \) carries a current of \( 0.2\, A \). What is the voltage drop across it?
A · \( 4 V \)
Using \( V = IR = 0.2 \times 20 = 4\, V \).
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Refer to the diagram showing two resistors \( R_1 = 4 \Omega \) and \( R_2 = 6 \Omega \) connected in series across a 12 V battery. Calculate the total current flowing in the circuit.
D · \( 1 A \)
Total resistance \( R = 4 + 6 = 10 \Omega \). Current \( I = \frac{V}{R} = \frac{12}{10} = 1 A \).
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In a circuit consisting of resistors in parallel, which form of Ohm's Law is used to calculate the voltage across each resistor?
A · Voltage across each resistor is the same
In parallel circuits, voltage is the same across all parallel branches, so Ohm's Law can be applied individually using this voltage for each resistor.
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Refer to the circuit below with two resistors \( R_1 = 3 \Omega \) and \( R_2 = 6 \Omega \) in parallel connected to a 12 V supply. Calculate the total current supplied by the battery.
A · \( 6 A \)
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Which law states that the algebraic sum of currents entering a node is zero?
C · Kirchhoff's Current Law
Kirchhoff's Current Law (KCL) states that the sum of currents entering a junction equals the sum leaving it, so total current sum is zero.
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At a junction in an electrical circuit, the incoming currents are 3 A and 5 A, and one outgoing current is 6 A. What is the magnitude of the other outgoing current according to Kirchhoff's Current Law?
A · 2 A
Sum of incoming currents = sum of outgoing currents. So, 3 + 5 = 6 + x \( \Rightarrow x = 2 A \).
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Refer to the diagram below showing a node with currents \( I_1 = 4 A \) entering, \( I_2 = 2 A \) leaving, and two unknown currents \( I_3 \) and \( I_4 \) leaving. If \( I_3 = 3 A \), calculate \( I_4 \) using KCL.
C · \( 1 A \)
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Which of the following best describes Kirchhoff's Voltage Law (KVL)?
B · The algebraic sum of all voltages around any closed loop equals zero
KVL states that the total sum of voltages around any closed loop in a circuit is zero.
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Refer to the given loop circuit with resistors \( R_1=2\Omega \), \( R_2=3\Omega \), and a voltage supply \( V=12 V \). If the current in the loop is \( I \), apply KVL to find \( I \).
A · 2.4 A
By KVL, the sum of voltage drops is equal to the supplied voltage:\( 12 = I \times 2 + I \times 3 = 5I \Rightarrow I = \frac{12}{5} = 2.4 A \).
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In the following closed loop with three resistors \( R_1 = 2 \Omega \), \( R_2 = 3 \Omega \), \( R_3 = 5 \Omega \) and a 10 V source, if current \( I \) flows clockwise, what is the value of \( I \) using KVL?
A · \( 1 A \)
Sum of resistances = 2 + 3 + 5 = 10 \( \Omega \). Applying KVL:\( 10 = I \times 10 \Rightarrow I = 1 A \).
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Refer to the diagram below. In the given two-loop circuit with resistors and voltage sources, apply KVL to find current \( I_1 \) assuming \( R_1=4\Omega \), \( R_2=2\Omega \), \( V_1=10V \), and \( V_2=5V \).
A · \( 1 A \)
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Refer to the diagram below showing a circuit with two junctions and three loops. Using both KCL and KVL, which statement is true about the currents \( I_1, I_2, I_3 \) in the circuit?
A · \( I_1 = I_2 + I_3 \) at a node
KCL states that sum of currents entering a node equals sum leaving, so \( I_1 = I_2 + I_3 \) generally holds at a junction.
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Which of the following describes the main purpose of Kirchhoff's laws in circuit analysis?
B · To ensure energy and charge conservation in complex circuits
Kirchhoff's laws help analyze complex electrical circuits by applying conservation of charge (KCL) and conservation of energy (KVL).
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Arrange the following steps correctly for applying Kirchhoff's Voltage Law to solve circuit problems.
A · Identify loops, assign polarities/voltage directions, write voltage sums = 0, solve equations
KVL requires identifying loops, assigning voltage polarities, writing equations with voltage sums = 0, then solving.
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For the circuit shown below consisting of two meshes, find the voltage \( V_x \) across resistor \( R = 5 \Omega \) carrying current 2 A using Ohm's Law.
A · 10 V
Voltage \( V_x = I \times R = 2 A \times 5 \Omega = 10 V \).
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Refer to the complex circuit diagram below with three loops and resistors connected. What is the best approach to find the currents in each branch?
D · Use both Kirchhoff's Laws and Ohm's Law simultaneously
In complex circuits, simultaneous application of Ohm's Law, KCL, and KVL is required to solve for unknown currents and voltages.
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In the circuit shown below, if the currents at the junction satisfy \( I_1 + I_2 = I_3 \) and applying Ohm's Law gives \( V_1 = 20 V \) and \( V_2 = 30 V \), determine the voltage \( V_3 \) across the third branch.
A · 50 V
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Ohm's Law is mathematically expressed as \( V = IR \). What does each symbol represent?
A · V = Voltage, I = Current, R = Resistance
Ohm's Law states that voltage (V) across a resistor is equal to the current (I) flowing through it multiplied by the resistance (R).
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Which of the following statements correctly describes Ohm's Law?
A · Current is directly proportional to voltage and inversely proportional to resistance.
Ohm's Law expresses that current \(I\) is directly proportional to voltage \(V\) and inversely proportional to resistance \(R\); i.e., \(I=\frac{V}{R}\).
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Refer to the diagram below. Calculate the voltage across the resistor if the current flowing is 3 A and the resistance is 4 Ω.
A · 12 V
Using Ohm's Law \(V = IR = 3 \times 4 = 12\) volts.
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A conductor has a voltage of 10 V across it and a current of 2 A flows through it. What is the resistance of the conductor?
A · 5 Ω
Resistance \(R = \frac{V}{I} = \frac{10}{2} = 5\) ohms.
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If the resistance in a circuit doubles while the voltage remains constant, what happens to the current according to Ohm's Law?
A · It halves
From Ohm's Law, current \(I = \frac{V}{R}\). If resistance \(R\) doubles, current \(I\) halves.
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Which of the following is NOT a limitation of Ohm's Law?
D · It is applicable to all materials regardless of temperature.
Ohm's Law is not applicable to all materials especially when temperature changes or in non-linear devices, thus statement D is incorrect.
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Why does Ohm's Law fail for semiconductor devices like diodes?
A · Because these devices have non-linear voltage-current characteristics.
Semiconductor devices like diodes exhibit non-linear voltage-current characteristics, hence Ohm's Law, which assumes linearity, does not hold.
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Refer to the diagram below. Which condition illustrates a limitation of Ohm's Law?
B · Voltage across diode changes non-linearly with current.
Diodes have non-linear V-I characteristics, illustrating Ohm’s Law limitations.
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Which of the following is a practical application of Ohm's Law?
A · Calculating the value of resistors in electrical circuits.
Ohm's Law is widely used to calculate voltage, current or resistance values in electrical circuits for designing and analyzing resistors.
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You need to find the current flowing through a 12 Ω resistor connected across a 24 V battery. Using Ohm's Law, what is the current?
A · 2 A
Current \( I = \frac{V}{R} = \frac{24}{12} = 2 \) amperes.
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Refer to the diagram below. If the total voltage supplied is 30 V and resistors of 5 Ω and 10 Ω are connected in series, what is the current flowing through the circuit?
A · 2 A
Total resistance \(R = 5 + 10 = 15\) Ω; current \(I = \frac{V}{R} = \frac{30}{15} = 2\) A.
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State Kirchhoff's Current Law (KCL): At any node in an electrical circuit, the algebraic sum of currents is
A · Zero
KCL states that the sum of currents entering and leaving a node is zero, ensuring charge conservation.
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Refer to the diagram below. If currents \( I_1 = 3A \) and \( I_2 = 2A \) are entering a junction and \( I_3 \) is leaving, what is the value of \( I_3 \) according to KCL?
A · 5 A
Sum of currents entering = Sum of currents leaving \(\Rightarrow\) \(I_3 = I_1 + I_2 = 3 + 2 = 5\) A.
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Which of the following best describes Kirchhoff's Voltage Law (KVL)?
A · Sum of all voltages around a closed loop is zero.
KVL states that algebraic sum of voltages in any closed loop is zero (energy conservation in circuits).
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Refer to the circuit diagram below with a loop containing voltage sources of 12 V and 5 V and resistors with voltage drops of 7 V and 10 V respectively. Verify KVL for the loop.
A · Sum of voltages = 0, hence KVL is satisfied
Sum of voltage rises = 12 + 5 = 17 V; sum of voltage drops = 7 + 10 = 17 V; difference is zero, satisfying KVL.
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At a node, currents of 4 A and 3 A enter, and currents of 2 A and 5 A leave. Is Kirchhoff's Current Law satisfied at this node?
A · Yes, sum of currents entering equals sum leaving
Sum entering = 4 + 3 = 7 A, sum leaving = 2 + 5 = 7 A; KCL is satisfied.
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Refer to the circuit diagram below. Apply KCL at node B where three branches meet with currents \( I_1 = 6A \), \( I_2 = 2A \) entering and \( I_3 \) leaving. What is \( I_3 \)?
A · 8 A
By KCL, sum of currents entering equals sum leaving: \( I_3 = I_1 + I_2 = 6 + 2 = 8\) A.
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In a closed electrical loop, the voltages measured are +10 V, -4 V, +6 V and -12 V. Do these voltages satisfy Kirchhoff's Voltage Law?
A · Yes, the sum is zero
Sum = 10 - 4 + 6 - 12 = 0, which satisfies KVL.
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Refer to the circuit below. Find the voltage drop across resistor R2 if \( R1 = 3 \Omega \), \( R2 = 6 \Omega \), and the total voltage supplied is 18 V in series.
A · 12 V
Total resistance \( R = 3 + 6 = 9 \Omega \). Current \(I = \frac{V}{R} = \frac{18}{9} = 2 A\). Voltage across R2 \(V_{R2} = IR2 = 2 \times 6=12 V\).
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Which of the following is TRUE when applying Kirchhoff's Laws to circuit analysis?
A · KCL is applied at nodes, KVL is applied in loops.
KCL applies to nodes (current summation), KVL applies to closed loops (voltage summation).
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Refer to the diagram below. Applying Kirchhoff's Voltage Law in loop ABCD, what is the missing voltage \(V_x\) given \(V_1=10V\), \(V_2=5V\), and \(V_3=8V\) with voltage polarities shown?
A · 3 V
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In a circuit loop, the voltage rises sum to 20 V and voltage drops sum to 15 V. What does this indicate with respect to Kirchhoff's Voltage Law?
A · KVL is violated since sums are not equal
KVL states the sum of voltage rises and drops must be equal (sum to zero algebraically). Difference indicates violation or error.
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In a two-loop circuit, if the currents are \( I_1 = 2 A \) and \( I_2 = 3 A \) flowing as shown in the diagram, what is the current through the resistor \( R = 5 \Omega \) common to both loops?
A · 1 A
Current through common resistor is the difference \( |I_1 - I_2| = |2 - 3| = 1 A \).
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Which of the following is the correct unit of magnetic flux density (B)?
A · Tesla (T)
Magnetic flux density \( B \) is measured in Tesla (T), which is equivalent to Wb/m².
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Refer to the diagram below of a solenoid with length \( l = 0.5 \ m \), number of turns \( N = 1000 \), and current \( I = 2 \, A \). What is the magnetic field intensity \( H \) inside the solenoid?
A · \( 4000 \, A/m \)
Magnetic field intensity \( H = \frac{NI}{l} = \frac{1000 \times 2}{0.5} = 4000 \, A/m \).Correct choice is 4000 A/m which is option A.
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Which quantity is directly induced in a conductor when it moves through a magnetic field?
A · Electromotive force (EMF)
When a conductor moves through a magnetic field, an electromotive force (EMF) is induced according to Faraday's law of induction.
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Refer to the diagram below showing a coil moving inside a magnetic field. If the magnetic flux linked with the coil changes from 0.05 Wb to 0.02 Wb in 0.01 seconds, what is the average induced emf in the coil?
A · \( 3 \, V \)
Average induced emf \( E = -\frac{\Delta \phi}{\Delta t} = -\frac{0.05 - 0.02}{0.01} = -3 \, V \), magnitude = 3 V.
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According to Faraday's first law of electromagnetic induction, the induced emf in a coil is directly proportional to which of the following?
A · Rate of change of magnetic flux
Faraday's first law states induced emf is directly proportional to the rate of change of magnetic flux linkage.
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Refer to the diagram below of a coil with 200 turns where the magnetic flux changes at a rate of 0.1 Wb/s. What is the induced emf in the coil according to Faraday's law?
A · \( 20 \, V \)
Induced emf \( E = N \frac{d\phi}{dt} = 200 \times 0.1 = 20 \, V \).
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Faraday's second law of electromagnetic induction states that the induced emf is equal to?
A · Negative rate of change of magnetic flux linkage
According to Faraday's second law, \( E = -\frac{d(N\phi)}{dt} \), negative indicating direction according to Lenz's law.
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Which law states that the direction of induced current is such that it opposes the cause producing it?
A · Lenz's Law
Lenz's Law states the induced current's direction opposes the change causing it, ensuring conservation of energy.
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Refer to the induction circuit below where a changing magnetic flux induces current in coil 2. According to Lenz's law, the direction of induced current in coil 2 will be such that it...
A · Opposes the change in magnetic flux due to coil 1
Lenz's law dictates induced current opposes the cause; thus it opposes the flux change from coil 1.
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Mutual inductance between two coils depends primarily on:
A · Number of turns and magnetic coupling between coils
Mutual inductance is proportional to the product of turns in each coil and their magnetic coupling (flux linkage).
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Self-inductance of a coil depends on:
A · Number of turns, coil length, and core material permeability
Self inductance depends on coil geometry and magnetic permeability of the core.
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Eddy currents are induced in a conducting material when subjected to a changing magnetic field. What is one primary effect of eddy currents?
A · Circular currents produce heat and energy losses
Eddy currents cause circulating loops of induced current that generate heat causing energy losses.
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In the diagram below, a metal plate rotates in a uniform magnetic field causing eddy currents. What is the primary application of this phenomenon?
A · Eddy current brakes in trains
Eddy currents produce resistive forces used in braking mechanisms like eddy current brakes for trains.
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Which of these is a ferromagnetic material with high permeability generally used in magnetic cores?
A · Iron
Iron is a ferromagnetic material with high permeability used in magnetic circuits.
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Which property of magnetic materials represents the ability to retain magnetization after removing the magnetizing force?
A · Retentivity
Retentivity is the property of a magnetic material to retain magnetism after the external field is removed.
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A charged particle moves perpendicular to a uniform magnetic field B. Which force acts on the particle?
A · Magnetic force perpendicular to velocity and magnetic field
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In the diagram below, a rectangular loop moves out of a magnetic field region. What will be the direction of the induced current in the loop according to Lenz's law?
B · Anticlockwise
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If the magnetic flux through a coil decreases at a constant rate of 0.1 Wb/s, what is the induced emf in a coil of 20 turns?
A · 2 V
Induced emf \( E = -N \frac{d\Phi}{dt} \). Given \( N=20 \), \( \frac{d\Phi}{dt} = 0.1 \, \text{Wb/s} \), so \( E = 20 \times 0.1 = 2 \, V \). Sign indicates direction.
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According to Faraday's law, the magnitude of induced emf in a coil is proportional to:
A · Rate of change of magnetic flux linkage
Faraday's law states \( E = -\frac{d\lambda}{dt} \), where \( \lambda = N\Phi \) is the flux linkage; emf depends on the rate of change of flux linkage.
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Refer to the circuit below. A coil of inductance 0.5 H experiences a change in current from 2 A to 5 A in 0.01 s. What is the average induced emf?
A · 150 V
Self-induction emf \( E = -L \frac{dI}{dt} \). \( \frac{dI}{dt} = \frac{5-2}{0.01} = 300 A/s \). So \( E = 0.5 \times 300 = 150 V \), but magnitude is 150 V. Careful with units.
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Which of the following statements regarding mutual induction is correct?
A · Voltage is induced in one coil due to change of current in another coil
Mutual induction occurs when a changing current in one coil induces emf in a nearby second coil via changing magnetic flux linkage.
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Refer to the diagram showing two coupled coils with mutual inductance M. If the current in Coil 1 changes at rate 10 A/s and \( M = 0.2 \, H \), what is the induced emf in Coil 2?
A · 2 V
Induced emf in Coil 2: \( E = M \frac{dI_1}{dt} = 0.2 \times 10 = 2 \, V \).
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Which factor primarily causes eddy currents in a solid conducting material placed in a changing magnetic field?
A · Changing magnetic flux through the conductor
Eddy currents are induced loops of current inside conductors due to time-varying magnetic flux as per Faraday's law.
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Refer to the diagram showing a metal plate moving through a magnetic field region. How do eddy currents affect the motion of the plate?
A · They oppose the motion of the plate
Eddy currents produce magnetic fields that oppose the cause (the plate’s motion), thus exerting a damping force that opposes movement.
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Which of the following devices relies on the principle of electromagnetic induction to function?
A · Electric generator
Electric generators convert mechanical energy into electrical energy by electromagnetic induction, inducing emf in coils as magnets rotate.
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Refer to the flux linkage graph below for a coil in an electromagnetic induction experiment. Between which time interval is the induced emf maximum?
A · Between 2s and 3s
Induced emf is proportional to the rate of change of flux linkage. Maximum slope (steepest change) occurs between 2s and 3s, so emf is maximum there.
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In a coil, the changing magnetic flux induces an emf of 5 V. If the coil has 50 turns, what is the rate of change of magnetic flux linkage?
A · 0.1 Wb/s
Induced emf \( E = N \times \frac{d\Phi}{dt} \) so \( \frac{d\Phi}{dt} = \frac{E}{N} = \frac{5}{50} = 0.1 \) Wb/s.
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Refer to the following circuit with two coils having self-inductances \( L_1 = 4 H \), \( L_2 = 1 H \), and mutual inductance \( M = 2 H \). If current in Coil 1 changes at \( 3 A/s \), what is the emf induced in Coil 2?
A · 6 V
Induced emf in Coil 2 due to Coil 1: \( E = M \frac{dI_1}{dt} = 2 \times 3 = 6 V \).
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A coil with self-inductance L = 2 mH and resistance R = 4 Ω is connected to a source with emf ε(t) = 12 cos(1000t) V. Determine the instantaneous rate of change of magnetic flux linkage in the coil at t = π/2000 seconds.
D · dλ/dt = 10,400 Wb/s
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What is the primary advantage of using a three-phase system over a single-phase system?
A · It requires less conductor material for the same power transmission
A three-phase system supplies constant power and uses less conductor material for the same power transfer, making it more efficient than single-phase systems.
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In a balanced three-phase system, the sum of the instantaneous voltages of the three phases is:
C · Always zero
In a balanced three-phase system, the sum of three instantaneous voltages at any instant sums to zero due to their 120° phase displacement.
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Refer to the diagram below showing a three-phase supply system.
Which of the following correctly states the phase difference between the line voltages in a balanced system?
A · 120° between any two line voltages
The line voltages in a balanced three-phase system are separated by 120° from each other in terms of phase.
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Which of the following is NOT a characteristic of a star (Y) connection in three-phase systems?
B · Line voltage equals phase voltage
In a star connection, line voltage \( V_L = \sqrt{3} \times V_{ph} \), so line voltage is not equal to phase voltage.
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Refer to the diagrams below of star (Y) and delta (Δ) connections.
Which statement correctly describes the current relationships in the delta connection?
B · Line current is \( \sqrt{3} \) times phase current and lags phase current by 30°
In a delta connection, the line current \( I_L = \sqrt{3} \times I_{ph} \) and lags the phase current by 30°.
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What is the relationship between line and phase voltage in a balanced star-connected load?
B · Line voltage \(= \sqrt{3} \times V_{ph} \)
In a star connection, the line voltage is \( \sqrt{3} \) times the phase voltage due to 120° phase difference between phases.
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Refer to the phasor diagram shown below for a star-connected balanced load.
If the phase voltage is \( 230\,V \), what is the line voltage?
B · 400 V
Line voltage \( V_L = \sqrt{3} \times V_{ph} = \sqrt{3} \times 230 \approx 400 V \).
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In a balanced three-phase system supplying a load with power factor \( \cos \phi \), the formula for total active power is:
C · \( P = \sqrt{3} V_{L} I_{L} \cos \phi \)
The total active power in a balanced three-phase circuit is \( P = \sqrt{3} V_{L} I_{L} \cos \phi \).
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Refer to the vector diagram below showing line voltage and current in a balanced three-phase load.
If line voltage is 400 V and line current is 50 A with a power factor angle of 36.87°, what is the active power?
B · \( 15.0\,kW \)
Active power \( P = \sqrt{3} \times V_{L} \times I_{L} \times \cos \phi = 1.732 \times 400 \times 50 \times \cos 36.87^{\circ} \approx 15,000\,W (15 kW) \).
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Which of the following represents the formula for total reactive power in a balanced three-phase circuit?
A · \( Q = \sqrt{3} V_{L} I_{L} \sin \phi \)
Reactive power in a balanced three-phase system is given by \( Q = \sqrt{3} V_{L} I_{L} \sin \phi \).
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Refer to the circuit diagram below of a three-phase balanced load connected in delta.
If each phase load has an impedance of \( (8 + j6)\Omega \) and the line voltage is 415 V, what is the line current?
D · \( 50.6\,A \)
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Which of the following best describes an unbalanced load in a three-phase system?
C · The phase voltages are unequal in magnitude or phase angle
An unbalanced load results in unequal phase voltages or currents due to different impedances or faults causing magnitude or phase angle variations.
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Refer to the vector diagram of a three-phase unbalanced load shown below.
What is the effect of neutral displacement in the system?
A · Neutral point shifts causing unequal phase voltages
Neutral displacement occurs in unbalanced systems causing the neutral point to shift, resulting in unequal phase voltages.
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In a three-phase system, which instrument combination is commonly used to measure active power accurately?
B · Two wattmeters method
The two wattmeter method provides accurate measurement of active power in both balanced and unbalanced three-phase systems.
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Which one of the following is NOT a method of improving power factor in three-phase systems?
C · Adding inductors in series with load
Adding inductors increases lagging power factor and does not correct it; capacitors or synchronous condensers improve power factor by providing leading reactive power.
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Which of the following correctly describes a key characteristic of a three-phase system?
B · Three phase voltages are spaced 120° apart
In a three-phase system, the voltages are sinusoidal and displaced from each other by 120° in phase, providing steady power delivery.
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Identify which of the following is NOT a typical advantage of a three-phase electrical system over a single-phase system.
C · Simpler motor design requiring no starting mechanism
While three-phase motors have better starting torque, some single-phase motors do require starting mechanisms; the statement that three-phase motors require no starting mechanism is incorrect.
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In a balanced three-phase system, the phase voltages are 230 V each. What is the line voltage in a star-connected load?
B · 398 V
In star connection, line voltage \( V_L = \sqrt{3} \times V_{phase} = \sqrt{3} \times 230 \approx 398 V \).
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Refer to the diagram below of a balanced three-phase system connected in delta. If the line voltage is 400 V, what is the phase voltage across each load?
A · 400 V
In delta connection, the phase voltage equals the line voltage, so phase voltage is 400 V.
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Which of the following correctly defines the relationship between line current \( I_L \) and phase current \( I_{ph} \) in a star-connected balanced load?
A · \( I_L = I_{ph} \)
In star connection, line current equals phase current because each line conductor carries the current of one phase.
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Refer to the phasor diagram below of a balanced three-phase system. If the phase voltage \( V_{ph} = 120 \) V and phase current \( I_{ph} = 10 \) A with power factor 0.8 lagging, calculate the total active power \( P \).
A · \( 2.88 \text{ kW} \)
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In a three-phase system, if the apparent power \( S = 15 \text{ kVA} \) and reactive power \( Q = 9 \text{ kVAR} \), what is the power factor of the load?
C · 0.8 lagging
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Which type of load results in equal currents but different phase angles in the three lines of a three-phase system?
B · Unbalanced load
Unbalanced loads cause unequal phase angles and/or magnitudes of current in the three lines, whereas balanced loads maintain equal current magnitudes displaced by 120°.
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Refer to the circuit diagram below of a three-phase star-connected system with an unbalanced load. Which of the following statements is TRUE about the neutral current?
C · Neutral current flows only if the load is unbalanced
Neutral current exists only when the load is unbalanced because unbalanced phase currents do not cancel out in the neutral wire.
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In converting a delta-connected load to its equivalent star-connected load, the phase resistance in star \( R_Y \) is given by:
B · \( R_Y = \frac{R_\Delta}{3} \)
The standard formula for conversion is \( R_Y = \frac{R_\Delta}{3} \) where \( R_\Delta \) is the delta-connected resistance.
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Refer to the diagram below showing a delta-connected resistive load of 6 \( \Omega \) per phase. Calculate the equivalent resistance for the star-connected load.
B · 2 \( \Omega \)
Using the delta to star formula: \( R_Y = \frac{R_\Delta}{3} = \frac{6}{3} = 2 \Omega \).
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Which of the following correctly expresses total complex power \( S \) in a balanced three-phase system with line voltage \( V_L \), line current \( I_L \) and power factor angle \( \phi \)?
B · \( S = \sqrt{3} V_L I_L \angle \phi \)
Total complex power \( S = \sqrt{3} V_L I_L \angle \phi \) combines magnitude and phase angle, representing apparent power with power factor angle \( \phi \).
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Refer to the three-phase circuit diagram below. Using Kirchhoff's Voltage Law (KVL), find the phase voltages if line voltage is 415 V in a balanced star-connected load.
A · 240 V
Phase voltage in star connection \( V_{ph} = \frac{V_L}{\sqrt{3}} = \frac{415}{1.732} \approx 240 V \).
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Which Kirchhoff's law is most suitable to analyze currents at the junction points in a three-phase circuit with unbalanced loads?
B · Kirchhoff's Current Law (KCL)
Kirchhoff's Current Law (KCL) states that algebraic sum of currents entering a junction is zero, ideal for analyzing currents at junctions, especially in unbalanced systems.
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Among the following options, which correctly describes the relationship between line and phase voltages in a delta-connected three-phase system?
A · \( V_L = V_{ph} \)
In delta connections, line voltage equals phase voltage because each line is connected directly across each load.
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Refer to the diagram below of a balanced three-phase, four-wire star-connected load. The line voltage is 415 V and the load impedance per phase is \( (6 + j8) \) \( \Omega \). Calculate the total active power consumed.
C · 20.7 kW
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Which of the following statements is CORRECT regarding power in a balanced three-phase system?
A · Reactive power \( Q = \sqrt{3} V_L I_L \sin \phi \)
Reactive power in a balanced system is given by \( Q = \sqrt{3} V_L I_L \sin \phi \). Other options are incorrect by definition or factor.
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For a balanced three-phase system, Assertion (A): The sum of line voltages is always zero.
Reason (R): Line voltages form a closed vector loop in a balanced three-phase system.
Choose the most appropriate option:
A · Both A and R are true and R is the correct explanation of A
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What is the definition of power factor in an AC electrical circuit?
B · The ratio of active power to apparent power
Power factor is defined as the ratio of active power (real power) flowing to the load to the apparent power in the circuit.
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Why is power factor an important parameter in electrical systems?
A · It indicates the efficiency of current usage
Power factor indicates how effectively electrical power is being converted into useful work output. A low power factor means poor utilization of electrical power.
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Which of the following correctly describes a leading power factor?
C · Current leads voltage by some angle
A leading power factor occurs when the current leads the voltage, typically due to capacitive loads.
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Refer to the power triangle shown below. If the apparent power is 100 VA and the reactive power is 60 VAR, what is the type of power factor?
B · Lagging power factor
Since reactive power is positive, it indicates inductive load and current lags voltage, hence lagging power factor.
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What are the units of reactive power in an AC circuit?
B · Volt-Amperes Reactive (VAR)
Reactive power is measured in Volt-Amperes Reactive (VAR) as it represents the power stored and released by inductive and capacitive elements.
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In an AC circuit, which of the following represents reactive power?
C · Power that oscillates between source and reactive components
Reactive power is the power that oscillates between the source and the reactive components (inductors and capacitors) and does not perform any useful work.
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Given an AC circuit with active power \( P = 80 \text{ W} \) and reactive power \( Q = 60 \text{ VAR} \), what is the apparent power \( S \)?
A · \( 100\ \text{VA} \)
Apparent power \( S = \sqrt{P^2 + Q^2} = \sqrt{80^2 + 60^2} = \sqrt{6400 + 3600} = \sqrt{10000} = 100\ \text{VA} \).
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Refer to the power triangle diagram below where \( P = 50 \text{ W} \), \( Q = 86.6 \text{ VAR} \), and \( S = 100 \text{ VA} \). What is the power factor \( \cos\theta \)?
A · 0.5 lagging
Power factor \( = \frac{P}{S} = \frac{50}{100} = 0.5 \). Since reactive power is positive (inductive), the power factor is lagging.
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In an AC circuit, if the voltage is 230 V, current is 10 A, and the power factor is 0.8 lagging, what is the active power consumed?
A · \( 1840\ \text{W} \)
Active power \( P = VI\cos\theta = 230 \times 10 \times 0.8 = 1840 \text{W} \).
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Refer to the circuit diagram below where a load draws a current of 15 A at 230 V AC with a lagging power factor of 0.6. Calculate the reactive power \( Q \) consumed by the load.
D · \( 2760\ \text{VAR} \)
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Which of the following effects is NOT typically caused by poor power factor in an electrical system?
C · Lower energy bills for the consumer
Poor power factor leads to increased losses, reduced capacity, and voltage drops but does not lower energy bills; it usually increases bills.
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What is a common method to improve power factor in an industrial AC circuit?
A · Installing capacitors in parallel with the load
Adding capacitors in parallel provides leading reactive power which cancels the lagging reactive power of inductive loads, thus improving power factor.
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What is the definition of power factor in an AC electrical system?
A · Ratio of active power to apparent power
Power factor is defined as the ratio of active power (P) to apparent power (S), indicating the efficiency of power usage.
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Which of the following best describes the significance of a low power factor in an electrical system?
A · Causes higher transmission losses and lower system efficiency
A low power factor means more reactive power and thus higher current flows, causing increased losses and reduced efficiency.
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A motor operates at a power factor of 0.7 lagging. What is the primary effect of this lagging power factor on the supply system?
A · Increases the current drawn from the supply
A lagging power factor means heavy reactive power demand causing more current to flow, increasing losses and demand on the supply system.
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Reactive power is primarily associated with which of the following electrical components?
A · Inductors and capacitors
Reactive power is caused by energy storage in inductors and capacitors, resulting in current and voltage being out of phase.
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Which statement correctly explains reactive power in AC circuits?
A · It represents power stored and released by reactive elements, with no net energy transfer
Reactive power oscillates between source and load via inductors or capacitors, causing no net energy consumption but affecting the system current flow.
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An AC circuit has active power \( P = 300\,W \) and reactive power \( Q = 400\,VAR \). What is the apparent power \( S \)?
A · \( 500\,VA \)
Apparent power \( S = \sqrt{P^2 + Q^2} = \sqrt{300^2 + 400^2} = 500\,VA \).
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Which power factor improvement technique involves installing equipment to provide capacitive reactance to the system?
A · Use of capacitor banks
Capacitor banks supply leading reactive power to cancel lagging reactive power of inductive loads, improving power factor.
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A load draws 10 kW of active power at a power factor of 0.6 lagging. What size of capacitor (in kVAR) is required to correct the power factor to unity?
B · 12 kVAR
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In an AC circuit, the voltage and current are measured to be 230 V and 10 A respectively, with a phase difference of 30°. Calculate the power factor and the reactive power.
A · Power factor = 0.866, Reactive power = 1150 VAR
Power factor = cos 30° = 0.866 Apparent power \( S = V \times I = 230 \times 10 = 2300 VA \)Reactive power \( Q = S \sin \phi = 2300 \times 0.5 = 1150 VAR \)
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Which of the following materials is commonly used for the core of a transformer to reduce hysteresis losses?
B · Silicon steel
Silicon steel is used as transformer core material due to its high permeability and low hysteresis losses.
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Refer to the diagram below of a basic transformer construction. Which part of the transformer is responsible for inducing EMF by magnetic flux linkage?
C · Transformer core
The transformer core provides a low reluctance path for magnetic flux linking the primary and secondary windings, inducing EMF.
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Which type of transformer is primarily used to increase the voltage level in power transmission?
B · Step-up transformer
Step-up transformers increase the voltage from primary to secondary, suitable for long-distance power transmission.
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What is the fundamental working principle of a transformer?
B · Electromagnetic induction
A transformer operates on the principle of electromagnetic induction where a changing current in primary induces voltage in secondary winding.
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Changing current in the primary winding of a transformer induces an emf in the secondary winding due to which law?
B · Faraday's Law of electromagnetic induction
Faraday's law states that a time varying magnetic flux induces an electromotive force (emf) in a coil.
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Refer to the phasor diagram of an ideal transformer shown below. What does the phase difference between primary voltage and current indicate in an ideal transformer under no load?
C · Current is in phase with voltage
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What causes the voltage induced in the secondary winding of a transformer to be proportional to the ratio of number of turns in secondary and primary windings?
B · Faraday’s Law of electromagnetic induction
Faraday’s law states the emf induced is proportional to the rate of change of magnetic flux and the number of turns in the winding.
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Determine the EMF induced per turn \( E_t \) in a transformer if the primary voltage is 230 V and the number of primary turns is 460. (Assume ideal conditions.)
A · 0.5 V/turn
EMF per turn \( E_t = \frac{V}{N} = \frac{230}{460} = 0.5 \) V/turn.
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The EMF equation for an ideal transformer is \( E = 4.44 \times f \times N \times \Phi_m \). What does \( \Phi_m \) represent in this equation?
A · Maximum flux in the core
\( \Phi_m \) is the peak or maximum magnetic flux in the transformer core.
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A transformer has 200 primary turns and 50 secondary turns. If 240 V is applied to the primary, what is the secondary voltage assuming an ideal transformer?
A · 60 V
Using \( V_2 = V_1 \times \frac{N_2}{N_1} = 240 \times \frac{50}{200} = 60 \) V.
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Which type of loss in transformers is due to eddy currents induced in the core?
C · Eddy current loss
Eddy currents are circulating currents induced in transformer core causing energy loss as heat.
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A transformer has copper losses of 500 W and iron losses of 300 W. If input power is 10 kW and output power is 9.2 kW, what is the efficiency approximately?
B · 92%
Efficiency = \( \frac{Output}{Input} \times 100 = \frac{9200}{10000} \times 100 = 92\% \).
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Which of the following improves transformer efficiency at full load?
C · Use copper with lower resistance
Copper losses decrease with better conductivity copper reducing I²R losses, thereby improving efficiency at full load.
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Refer to the equivalent circuit of a transformer shown below. What does the component labeled \( R_c \) represent?
A · Core loss resistance
\( R_c \) models the core (iron) losses like hysteresis and eddy current losses in parallel with magnetizing reactance.
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In the equivalent circuit of a transformer, what does the series reactance \( X_l \) represent?
B · Leakage reactance
Series reactance \( X_l \) represents leakage reactance due to leakage flux not linking both windings.
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Refer to the simplified phasor diagram below of a loaded transformer. What is the correct relation of the secondary voltage \( V_2 \) with primary voltage \( V_1 \) and drop across resistance and reactance?
B · \( V_1 = V_2 + I_1 (R + jX) \)
Primary voltage equals secondary voltage plus voltage drops across series resistance and leakage reactance.
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The open circuit test on a transformer is primarily used to determine which parameter(s)?
B · Core losses and magnetizing current
Open circuit test measures core losses and magnetizing current since the transformer is run at rated voltage but no load.
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In a short circuit test of a transformer, which parameter is mainly measured?
B · Copper losses and equivalent series impedance
Short circuit test determines copper losses and equivalent series impedance by applying reduced voltage to cause rated current.
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Refer to the testing setup diagram below for the open circuit test on a transformer. What instrument is connected in the primary side to measure the no load current?
B · Ammeter
An ammeter is used in the primary circuit to measure no load current during the open circuit test.
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During the short circuit test of a transformer, the applied voltage is typically:
B · Very low (around 5-10% of rated voltage)
Only a small voltage is applied in short circuit test to circulate rated current through the windings without damaging the transformer.
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In a transformer open circuit test, which loss is predominantly measured?
B · Iron loss
Iron loss (core loss) is primarily measured in the open circuit test since the current is low and copper loss is negligible.
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Refer to the phasor diagram of a loaded transformer below. If the primary current \( I_1 \) leads the primary voltage \( V_1 \) by angle \( \phi \), what does this indicate about the load power factor?
B · Load power factor is leading
When current leads voltage, the load power factor is leading, typical of capacitive loads.
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Which of the following materials is commonly used for the core of a transformer to reduce hysteresis loss?
A · Silicon steel
Silicon steel is used in transformer cores because its properties reduce hysteresis and eddy current losses, improving efficiency.
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Identify the component of a transformer responsible for providing a low reluctance path for the magnetic flux.
A · Core
The core is made of ferromagnetic material and provides a low reluctance path for magnetic flux linking primary and secondary windings.
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Which part of a transformer reduces eddy current losses in the core?
A · Laminated core
The core is laminated to restrict eddy currents to small loops, thereby reducing eddy current losses effectively.
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Refer to the diagram below of a transformer core and windings. Which part is labelled as the primary winding?
A · Left coil with input voltage
The primary winding is the coil connected to the input AC supply, typically shown on one side of the transformer core.
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In a transformer, the emf is induced in the secondary winding because of which phenomenon?
A · Mutual induction
An alternating current in the primary winding creates a changing magnetic flux which induces an emf in the secondary winding by mutual induction.
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What is the relationship between the voltages and number of turns in an ideal transformer?
A · \( \frac{V_p}{V_s} = \frac{N_p}{N_s} \)
In an ideal transformer, the voltage ratio equals the turns ratio: primary voltage to secondary voltage equals primary turns to secondary turns.
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Refer to the diagram below showing the phasor diagram of an ideal transformer. What does the phasor \( E_p \) represent?
A · Induced emf in primary winding
\( E_p \) represents the induced emf in the primary winding caused by alternating flux in the transformer core.
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Which of the following correctly describes the working principle of a transformer?
A · It works on the principle of mutual induction between primary and secondary coils
A transformer operates on mutual induction where an alternating current in the primary coil induces an emf in the secondary coil.
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What effect does increasing the frequency of the input AC supply have on the transformer operation assuming constant flux density?
A · Induced emf increases proportionally
According to Faraday's law, the induced emf \( E = 4.44 f N \Phi_m \); increasing frequency \( f \) increases the emf.
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Which type of transformer is primarily used to step down high transmission line voltages to distribution voltages?
A · Distribution transformer
Distribution transformers reduce high voltages from transmission lines to levels suitable for consumer use.
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Which of the following transformers has a single winding that acts as both primary and secondary winding?
A · Auto-transformer
An auto-transformer uses a single continuous winding tapped at some point to provide different voltage levels.
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Which transformer is used to measure large currents by producing a proportional smaller current for instruments?
A · Current transformer
Current transformers reduce high current levels to measurable low currents for metering and protection devices.
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A 230 V primary winding has 500 turns. The secondary winding has 200 turns. What is the voltage across the secondary winding?
A · 92 V
Using the transformer formula \( V_s = V_p \times \frac{N_s}{N_p} = 230 \times \frac{200}{500} = 92 V \).
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Refer to the equivalent circuit diagram of a transformer below. Which component represents the primary winding resistance?
A · \( R_1 \)
\( R_1 \) in the equivalent circuit represents the resistance of the primary winding causing copper loss.
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In a transformer's equivalent circuit, what does the component \( X_m \) represent?
A · Magnetizing reactance
\( X_m \) models the magnetizing reactance representing the magnetizing current needed to establish the flux in the core.
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Refer to the transformer equivalent circuit diagram below. Which branch accounts for the core losses?
A · \( R_c \) branch
\( R_c \) branch models the core or iron losses (hysteresis and eddy currents) in the transformer core.
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Which loss in a transformer is caused by current flowing through the resistance of the windings?
A · Copper loss
Copper loss arises due to resistive heating when current flows through the transformer's windings.
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Which transformer loss depends on the magnetic properties of the core material and the frequency of operation?
A · Hysteresis Loss
Hysteresis loss depends on core material properties and frequency of magnetization cycles per second.
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In a transformer test, the iron loss is determined by which testing method?
A · Open circuit test
Open circuit test is performed at rated voltage and no load to measure the iron losses and core characteristics.
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Which of the following tests on a transformer is used to primarily determine the copper losses?
A · Short circuit test
Short circuit test is done by shorting the secondary and applying reduced voltage on primary to measure copper losses.
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What is the efficiency of a transformer operating at full load if the output power is 10 kW and total losses are 500 W?
A · 95%
Efficiency = \( \frac{Output}{Output + Losses} = \frac{10000}{10000+500} = 0.952 = 95.2\% \) approx 95%.
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Refer to the circuit diagram below of a transformer. Which component measures the input power during an open circuit test?
A · Wattmeter connected on primary
In an open circuit test, wattmeter connected on the primary side measures input power which approximates iron losses.
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Which one of the following is NOT an application of transformers?
B · Rectification of AC to DC
Transformers do not perform rectification; they can only transfer AC power with voltage transformation or isolation.
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During a short circuit test on a transformer, what is the primary voltage typically adjusted to?
A · A small value to produce rated current in the winding
In a short circuit test, a reduced voltage is applied to produce full load current, minimizing core losses so copper losses dominate measurement.
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Refer to the transformer circuit diagram below. If primary voltage \( V_p = 240 V \), turns ratio \( N_p:N_s = 4:1 \), what is the secondary voltage \( V_s \)?
A · 60 V
Using \( V_s = V_p \times \frac{N_s}{N_p} = 240 \times \frac{1}{4} = 60 V \).
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Which of the following is a commonly used rechargeable battery type in automotive applications?
A · Lead-acid battery
Lead-acid batteries are widely used in automotive applications due to their ability to deliver high surge currents and cost-effectiveness.
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Which battery type utilizes nickel oxide hydroxide and cadmium as electrodes?
A · Ni-Cd battery
Ni-Cd batteries use nickel oxide hydroxide as positive electrode and cadmium as negative electrode.
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Which type of battery is known for having a high energy density and is widely used in portable electronics?
A · Lithium-ion battery
Lithium-ion batteries have a high energy density which makes them suitable for portable electronic devices.
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What is the primary advantage of Lithium-ion batteries over Lead-acid batteries?
A · Higher energy density
Lithium-ion batteries offer higher energy density, making them lighter and more compact compared to lead-acid batteries.
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Which of the following batteries suffers from the 'memory effect' if not properly charged and discharged?
A · Nickel-Cadmium (Ni-Cd)
Ni-Cd batteries tend to develop memory effect, reducing their capacity if they are not fully discharged before recharge.
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Which charging method maintains a constant current throughout the charging process until the battery reaches a specified voltage?
A · Constant current charging
Constant current charging keeps the charging current steady until the battery voltage reaches the desired level.
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In trickle charging, the charging current is typically:
A · Very low, equal to the battery's self-discharge current
Trickle charging supplies a small current matching the battery’s self-discharge to keep it fully charged.
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Refer to the diagram below showing a simple constant current charging circuit for a lead-acid battery. Which component limits the current to a safe charging value?
A · Resistor R1
The resistor R1 limits the charging current to prevent damage to the battery during constant current charging.
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Which charging method is most suitable for lithium-ion batteries to prevent overcharging and prolong battery life?
A · Constant current followed by constant voltage
Lithium-ion batteries are commonly charged using a constant current phase followed by a constant voltage phase to optimize charging and prevent damage.
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What is the main disadvantage of constant voltage charging for lead-acid batteries?
A · Initial charging current can be too high causing damage
In constant voltage charging, a high initial current may flow if the battery voltage is much lower, possibly damaging the battery.
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Refer to the charging characteristic curve shown below for a Ni-Cd battery. What does the plateau region in the voltage vs. time curve represent during charging?
A · Constant voltage phase
The voltage plateau represents the period when voltage remains almost constant as the battery charges under constant voltage conditions.
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Which charging characteristic is associated with a rapid drop in charging current as the lead-acid battery approaches full charge?
A · Decrease in charging current during constant voltage phase
In lead-acid batteries, current decreases rapidly in the constant voltage charging phase as the battery reaches full charge.
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What does the term 'charging efficiency' of a battery signify?
A · Ratio of energy stored to energy supplied during charging
Charging efficiency is the ratio of the useful energy stored in the battery to the total electrical energy supplied during charging.
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Which of the following statements is true about the charging time of Ni-Cd batteries compared to lead-acid batteries?
A · Ni-Cd batteries typically have shorter charging times
Ni-Cd batteries generally have faster charging times due to better charge acceptance and less sulfation issues compared to lead-acid batteries.
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Refer to the block diagram below representing a typical multi-stage charging method. What is the purpose of the final stage "Float Charge" shown?
A · Maintain battery at full charge with minimal current
The float charge stage supplies a low current to maintain full charge without overcharging, extending battery life.
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Which of the following factors is NOT typically considered when selecting a battery for a specific application?
C · Climate color
Climate color is irrelevant; important criteria include capacity, cost, weight, charging time, and applications.
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What is the main application of sealed maintenance-free (SMF) lead-acid batteries?
A · Uninterruptible Power Supplies (UPS)
SMF lead-acid batteries are commonly used in UPS systems due to their sealed design and reliable performance.
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Which selection criterion is most important for batteries used in electric vehicles?
A · High energy density and cycle life
Electric vehicles require batteries with high energy density and long cycle life to maximize range and durability.
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Which battery type would be MOST suitable for deep-cycle applications such as solar energy storage?
A · Deep-cycle lead-acid battery
Deep-cycle lead-acid batteries are designed for repeated deep discharges, making them suitable for renewable energy storage.
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What is the primary safety precaution when charging lead-acid batteries indoors?
A · Ensure proper ventilation to avoid buildup of explosive gases
Lead-acid battery charging can produce hydrogen gas, which is explosive, so ventilation is critical.
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Which maintenance step is important to avoid damage during battery charging?
A · Regularly checking electrolyte levels in flooded lead-acid batteries
Maintaining electrolyte levels prevents battery damage and ensures proper chemical reactions during charging.
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Which of the following can help in preventing thermal runaway during fast charging of batteries?
A · Temperature monitoring and controlled charging current
Thermal runaway can be avoided by monitoring temperature and regulating charging current accordingly.
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Refer to the diagram below showing the charging setup indicating the placement of a fuse and ammeter. What is the primary purpose of the fuse in this charging circuit?
A · Protect the charging circuit from overcurrent situations
The fuse protects wiring and components by breaking the circuit if excessive current flows.
