100 Important MCQs (Set-1 of Basic to Moderate level MCQs) on "Electromagnetic Induction", Physics (Unit-Wise MCQs Practice):
This post contains carefully selected Multiple-Choice Questions (MCQs) (Set-1 from Basic to Moderate Level) from Electromagnetism (Unit) of Physics, prepared strictly according to the latest board exam syllabus. These MCQs present a balanced mix of conceptual understanding and numerical problem-solving, making them revision-friendly, exam-oriented, and high-scoring.
Whether you are preparing for annual board examinations, chapter tests, or competitive entry tests, this comprehensive MCQ collection thoroughly covers the fundamental principles of Electromagnetism — starting from Magnetic Fields and Force on Current Carrying Conductors to Measuring Instruments and Digital Multimeters — helping students build strong conceptual clarity and numerical confidence.
🔹 This unit-wise MCQ set includes questions from:
• Magnetic Field and Magnetic Flux
• Force on a Current Carrying Conductor
• Ampere’s Law and Magnetic Field due to Solenoid
• Applications of Magnetic Field
• Motion of Charged Particle in Uniform Magnetic Field
• Determination of e/m for an Electron
• Velocity Selector
• Torque on a Current Carrying Loop / Coil
• MRI (Magnetic Resonance Imaging)
• Galvanometer – construction and working
• Conversion of Galvanometer into Ammeter and Voltmeter
• Avometer / Multimeter
• Current, Voltage, and Resistance Measurement
• Digital Multimeters
Each MCQ is provided with the correct answer and a clear, concise explanation, helping students to:
- Strengthen conceptual understanding of magnetic fields and electromagnetic forces
- Avoid common mistakes in numerical problems involving flux, torque, and charged particle motion
- Improve problem-solving skills for e/m calculations, velocity selector, and solenoid fields
- Master measuring instruments including galvanometer conversions and multimeters
- Achieve maximum marks in the MCQ section
This all-in-one Electromagnetism MCQ collection is an essential revision tool for students aiming to excel in Physics exams and fully master the concepts of magnetic fields, moving charges, electromagnetic torque, and electrical measuring instruments.
SECTION–A (Basic Concepts)
MCQ No. 1
Electromagnetic induction was discovered by:
a) Maxwell
b) Faraday
c) Ampere
d) Gauss
Correct answer: b) Faraday
Explanation:
Michael Faraday discovered electromagnetic induction in 1831.
MCQ No. 2
Magnetic flux is defined as:
a) Product of B and area
b) B/A
c) B × volume
d) B × length
Correct answer: a) Product of B and area
Explanation:
Φ = B A cosθ.
MCQ No. 3
SI unit of magnetic flux is:
a) Tesla
b) Weber
c) Henry
d) Volt
Correct answer: b) Weber
Explanation:
1 Weber = 1 Tesla·m².
MCQ No. 4
Induced emf is proportional to:
a) Flux
b) Change in flux
c) Square of flux
d) Resistance
Correct answer: b) Change in flux
Explanation:
Faraday’s law: E ∝ dΦ/dt.
MCQ No. 5
Lenz’s law is based on conservation of:
a) Charge
b) Energy
c) Momentum
d) Mass
Correct answer: b) Energy
Explanation:
It ensures no violation of conservation of energy.
MCQ No. 6
If magnetic flux through coil remains constant, induced emf is:
a) Maximum
b) Zero
c) Constant
d) Infinite
Correct answer: b) Zero
Explanation:
No change in flux → no induced emf.
MCQ No. 7
Direction of induced current is given by:
a) Right-hand rule
b) Fleming’s right-hand rule
c) Fleming’s left-hand rule
d) Corkscrew rule
Correct answer: b) Fleming’s right-hand rule
Explanation:
Used for generator action.
MCQ No. 8
Emf induced due to change in its own current is called:
a) Mutual induction
b) Self induction
c) Motional emf
d) Eddy current
Correct answer: b) Self induction
Explanation:
Inductor opposes change in its own current.
MCQ No. 9
Unit of inductance is:
a) Weber
b) Tesla
c) Henry
d) Volt
Correct answer: c) Henry
Explanation:
1 Henry = 1 V·s/A.
MCQ No. 10
If number of turns increases, induced emf:
a) Decreases
b) Increases
c) Same
d) Zero
Correct answer: b) Increases
Explanation:
E = –N(dΦ/dt). Directly proportional to N.
MCQ No. 11
Motional emf is maximum when rod moves:
a) Parallel to B
b) Perpendicular to B
c) At 45°
d) At 0°
Correct answer: b) Perpendicular to B
Explanation:
E = Bℓv sinθ; maximum at 90°.
MCQ No. 12
If magnetic field reverses direction completely, flux change is:
a) Φ
b) 2Φ
c) Zero
d) Φ/2
Correct answer: b) 2Φ
Explanation:
From +Φ to –Φ gives total change 2Φ.
MCQ No. 13
Induced current always opposes:
a) Magnetic field
b) Cause producing it
c) Voltage
d) Resistance
Correct answer: b) Cause producing it
Explanation:
Statement of Lenz’s law.
MCQ No. 14
If a magnet is stationary inside a coil, induced emf is:
a) Zero
b) Maximum
c) Constant
d) Increasing
Correct answer: a) Zero
Explanation:
No change in flux.
MCQ No. 15
Magnetic flux is maximum when angle between B and area vector is:
a) 0°
b) 30°
c) 60°
d) 90°
Correct answer: a) 0°
Explanation:
Φ = BA cosθ.
MCQ No. 16
Self inductance depends on:
a) Number of turns
b) Core material
c) Area of coil
d) All of these
Correct answer: d) All of these
Explanation:
L depends on geometry and permeability.
MCQ No. 17
Eddy currents are produced due to:
a) Constant magnetic field
b) Changing magnetic field
c) Electric field
d) Heat
Correct answer: b) Changing magnetic field
Explanation:
They are induced currents in bulk conductors.
MCQ No. 18
AC generator works on principle of:
a) Self induction
b) Electromagnetic induction
c) Electrostatics
d) Capacitor effect
Correct answer: b) Electromagnetic induction
Explanation:
Rotating coil changes flux.
MCQ No. 19
Transformer works only on:
a) DC
b) AC
c) Both
d) Static charge
Correct answer: b) AC
Explanation:
Requires changing magnetic flux.
MCQ No. 20
Time constant of RL circuit equals:
a) R/L
b) L/R
c) RL
d) 1/RL
Correct answer: b) L/R
Explanation:
τ = L/R.
MCQ No. 21
Induced emf in coil is zero when coil rotates with:
a) Zero angular speed
b) Maximum speed
c) Variable speed
d) High frequency
Correct answer: a) Zero angular speed
Explanation:
No change in flux.
MCQ No. 22
Magnetic energy stored in inductor is proportional to:
a) I
b) I²
c) 1/I
d) L only
Correct answer: b) I²
Explanation:
U = ½LI².
MCQ No. 23
Increasing permeability of core:
a) Decreases inductance
b) Increases inductance
c) No effect
d) Makes emf zero
Correct answer: b) Increases inductance
Explanation:
L ∝ μ.
MCQ No. 24
If coil area doubles, flux becomes:
a) Same
b) Double
c) Half
d) Zero
Correct answer: b) Double
Explanation:
Φ = BA.
MCQ No. 25
When induced emf is maximum, flux is:
a) Maximum
b) Zero
c) Half
d) Constant
Correct answer: b) Zero
Explanation:
At zero flux, rate of change is maximum.
SECTION–B (Numerical Applications)
MCQ No. 26
A coil of 200 turns has magnetic flux of 0.01 Wb through each turn. If flux becomes zero in 0.2 s, induced emf is:
a) 5 V
b) 10 V
c) 15 V
d) 20 V
Correct answer: b) 10 V
Explanation:
E = N(ΔΦ/Δt)
= 200 × (0.01 / 0.2)
= 200 × 0.05 = 10 V.
MCQ No. 27
A rod 0.5 m long moves with velocity 4 m/s perpendicular to magnetic field 0.8 T. Induced emf is:
a) 1.6 V
b) 0.8 V
c) 3.2 V
d) 2 V
Correct answer: a) 1.6 V
Explanation:
E = Bℓv = 0.8 × 0.5 × 4 = 1.6 V.
MCQ No. 28
If inductance of coil is 2 H and current changes at rate 3 A/s, induced emf is:
a) 6 V
b) 5 V
c) 3 V
d) 1.5 V
Correct answer: a) 6 V
Explanation:
E = L(dI/dt) = 2 × 3 = 6 V.
MCQ No. 29
Energy stored in 4 H inductor carrying 3 A current:
a) 18 J
b) 36 J
c) 6 J
d) 9 J
Correct answer: a) 18 J
Explanation:
U = ½LI² = ½ × 4 × 9 = 18 J.
MCQ No. 30
A transformer has 500 primary turns and 100 secondary turns. If primary voltage is 220 V, secondary voltage is:
a) 44 V
b) 110 V
c) 22 V
d) 11 V
Correct answer: a) 44 V
Explanation:
Vs/Vp = Ns/Np = 100/500 = 1/5
Vs = 220 × 1/5 = 44 V.
MCQ No. 31
If current in RL circuit reaches 63% in 2 s, time constant is:
a) 1 s
b) 2 s
c) 3 s
d) 4 s
Correct answer: b) 2 s
Explanation:
At t = τ, current reaches 63% of maximum.
MCQ No. 32
A 300-turn coil has area 0.02 m² placed in magnetic field 0.5 T perpendicular to it. Magnetic flux is:
a) 3 Wb
b) 0.01 Wb
c) 0.3 Wb
d) 30 Wb
Correct answer: a) 3 Wb
Explanation:
Φ = NBA
= 300 × 0.5 × 0.02
= 300 × 0.01 = 3 Wb.
MCQ No. 33
If magnetic field increases from 0 to 0.4 T in 0.1 s over area 0.5 m², induced emf in single turn loop is:
a) 1 V
b) 2 V
c) 0.5 V
d) 0.2 V
Correct answer: b) 2 V
Explanation:
ΔΦ = BA = 0.4 × 0.5 = 0.2
E = 0.2 / 0.1 = 2 V.
MCQ No. 34
An AC generator produces peak emf 200 V. RMS value is:
a) 200 V
b) 100 V
c) 141 V
d) 70 V
Correct answer: c) 141 V
Explanation:
Erms = E₀ / √2 = 200 / 1.414 ≈ 141 V.
MCQ No. 35
If L = 6 H and R = 3 Ω, time constant is:
a) 1 s
b) 2 s
c) 3 s
d) 6 s
Correct answer: b) 2 s
Explanation:
τ = L/R = 6/3 = 2 s.
MCQ No. 36
A coil rotates at angular speed 100 rad/s in magnetic field. If speed doubles, induced emf becomes:
a) Same
b) Double
c) Half
d) Four times
Correct answer: b) Double
Explanation:
E₀ = NBAω → proportional to ω.
MCQ No. 37
If flux changes from 0.02 Wb to 0.05 Wb in 0.1 s in a 100-turn coil, induced emf is:
a) 10 V
b) 20 V
c) 30 V
d) 3 V
Correct answer: c) 30 V
Explanation:
ΔΦ = 0.03
E = 100 × (0.03 / 0.1) = 100 × 0.3 = 30 V.
MCQ No. 38
If current in inductor decreases uniformly from 5 A to 1 A in 2 s and L = 4 H, induced emf magnitude is:
a) 4 V
b) 8 V
c) 16 V
d) 10 V
Correct answer: b) 8 V
Explanation:
E = L(ΔI/Δt) = 4 × (4/2) = 4 × 2 = 8 V.
MCQ No. 39
If coil area is 0.1 m² and B = 0.2 T at 60°, flux is:
a) 0.02 Wb
b) 0.01 Wb
c) 0.1 Wb
d) 0.2 Wb
Correct answer: b) 0.01 Wb
Explanation:
Φ = BA cosθ
= 0.2 × 0.1 × cos60°
= 0.02 × 0.5 = 0.01 Wb.
MCQ No. 40
If number of turns increases from 100 to 200, induced emf becomes:
a) Same
b) Double
c) Half
d) Four times
Correct answer: b) Double
Explanation:
E ∝ N.
MCQ No. 41
A 5 H inductor carries 4 A. Energy stored is:
a) 20 J
b) 40 J
c) 80 J
d) 10 J
Correct answer: b) 40 J
Explanation:
U = ½LI² = ½ × 5 × 16 = 40 J.
MCQ No. 42
If frequency of AC is 50 Hz, period is:
a) 0.02 s
b) 0.2 s
c) 0.002 s
d) 2 s
Correct answer: a) 0.02 s
Explanation:
T = 1/f = 1/50 = 0.02 s.
MCQ No. 43
In step-up transformer, if Ns/Np = 5, voltage increases by:
a) 2 times
b) 5 times
c) 10 times
d) 1/5
Correct answer: b) 5 times
Explanation:
Voltage ratio equals turns ratio.
MCQ No. 44
If inductance is 3 H and current increases at 2 A/s, emf is:
a) 6 V
b) 5 V
c) 1.5 V
d) 3 V
Correct answer: a) 6 V
Explanation:
E = L(dI/dt) = 3 × 2 = 6 V.
MCQ No. 45
Magnetic flux through loop is zero when θ equals:
a) 0°
b) 30°
c) 90°
d) 180°
Correct answer: c) 90°
Explanation:
Φ = BA cos90° = 0.
MCQ No. 46
If coil rotates at 10 revolutions per second, frequency is:
a) 5 Hz
b) 10 Hz
c) 20 Hz
d) 100 Hz
Correct answer: b) 10 Hz
Explanation:
Frequency equals revolutions per second.
MCQ No. 47
A 2 m rod moves at 3 m/s in 0.5 T perpendicular field. Induced emf:
a) 1 V
b) 2 V
c) 3 V
d) 6 V
Correct answer: c) 3 V
Explanation:
E = Bℓv = 0.5 × 2 × 3 = 3 V.
MCQ No. 48
If permeability doubles, inductance becomes:
a) Same
b) Half
c) Double
d) Four times
Correct answer: c) Double
Explanation:
L ∝ μ.
MCQ No. 49
If current becomes constant in RL circuit, induced emf becomes:
a) Maximum
b) Zero
c) Double
d) Infinite
Correct answer: b) Zero
Explanation:
dI/dt = 0.
MCQ No. 50
Peak voltage of AC is 170 V. RMS voltage is:
a) 120 V
b) 170 V
c) 85 V
d) 240 V
Correct answer: a) 120 V
Explanation:
Erms = 170 / 1.414 ≈ 120 V.
🔹 SECTION–C (Inductance & RL Circuits – Mixed Concepts)
MCQ No. 51
An inductor of 8 H is connected in series with 4 Ω resistor. Time constant of the circuit is:
a) 0.5 s
b) 1 s
c) 2 s
d) 4 s
Correct answer: c) 2 s
Explanation:
τ = L/R = 8/4 = 2 s.
MCQ No. 52
If resistance in RL circuit is doubled, time constant becomes:
a) Double
b) Half
c) Same
d) Four times
Correct answer: b) Half
Explanation:
τ = L/R. Increasing R decreases τ.
MCQ No. 53
At t = 3τ, current in RL circuit is approximately:
a) 50%
b) 63%
c) 95%
d) 100%
Correct answer: c) 95%
Explanation:
After 3τ, current reaches about 95% of final value.
MCQ No. 54
Inductance of a coil increases if:
a) Length increases
b) Number of turns decreases
c) Core is removed
d) Area increases
Correct answer: d) Area increases
Explanation:
L ∝ NAμ / length. Increasing area increases inductance.
MCQ No. 55
If L = 10 H and R = 5 Ω, current reaches 63% in:
a) 1 s
b) 2 s
c) 5 s
d) 10 s
Correct answer: b) 2 s
Explanation:
τ = L/R = 10/5 = 2 s.
MCQ No. 56
Energy stored in 2 H inductor carrying 6 A is:
a) 36 J
b) 12 J
c) 24 J
d) 18 J
Correct answer: a) 36 J
Explanation:
U = ½LI² = ½ × 2 × 36 = 36 J.
MCQ No. 57
If number of turns becomes three times, inductance becomes:
a) 3L
b) 6L
c) 9L
d) L/3
Correct answer: c) 9L
Explanation:
L ∝ N².
MCQ No. 58
When battery is disconnected, current in RL circuit:
a) Stops instantly
b) Decreases gradually
c) Increases
d) Becomes constant
Correct answer: b) Decreases gradually
Explanation:
Inductor opposes sudden change in current.
MCQ No. 59
The unit Henry is equivalent to:
a) V·s/A
b) V/A
c) A·s/V
d) Wb/m
Correct answer: a) V·s/A
Explanation:
From definition of inductance.
MCQ No. 60
If inductance is 4 H and dI/dt = 5 A/s, induced emf is:
a) 10 V
b) 15 V
c) 20 V
d) 25 V
Correct answer: c) 20 V
Explanation:
E = L(dI/dt) = 4 × 5 = 20 V.
MCQ No. 61
In steady state DC, inductor behaves like:
a) Open circuit
b) Short circuit
c) Capacitor
d) Battery
Correct answer: b) Short circuit
Explanation:
After steady state, inductor offers negligible resistance.
MCQ No. 62
If resistance is zero in RL circuit, time constant becomes:
a) Zero
b) Infinite
c) One
d) Constant
Correct answer: b) Infinite
Explanation:
τ = L/R → if R = 0, τ → ∞.
MCQ No. 63
Self-inductance mainly depends on:
a) Frequency
b) Geometry of coil
c) Applied voltage
d) Current value
Correct answer: b) Geometry of coil
Explanation:
It depends on turns, area, length and core.
MCQ No. 64
At t = τ, voltage across resistor equals:
a) 63% of supply
b) 37% of supply
c) 100%
d) Zero
Correct answer: a) 63% of supply
Explanation:
Voltage across R follows current rise.
MCQ No. 65
Magnetic energy density in inductor depends on:
a) Voltage
b) Current
c) Magnetic field
d) Resistance
Correct answer: c) Magnetic field
Explanation:
Energy stored in magnetic field region.
MCQ No. 66
If current changes very rapidly, induced emf becomes:
a) Small
b) Large
c) Zero
d) Constant
Correct answer: b) Large
Explanation:
E ∝ dI/dt.
MCQ No. 67
If length of solenoid doubles (others constant), inductance:
a) Double
b) Half
c) Same
d) Four times
Correct answer: b) Half
Explanation:
L ∝ 1/length.
MCQ No. 68
An RL circuit has τ = 4 s. After 8 s, current is approximately:
a) 63%
b) 86%
c) 95%
d) 98%
Correct answer: d) 98%
Explanation:
At 2τ → about 86%, at 3τ → 95%, at 4τ → 98%.
MCQ No. 69
If inductance increases, time constant:
a) Increases
b) Decreases
c) Same
d) Zero
Correct answer: a) Increases
Explanation:
τ = L/R.
MCQ No. 70
When switch is closed, induced emf in inductor is:
a) Zero
b) Equal to supply (opposite direction)
c) Half
d) Double
Correct answer: b) Equal to supply (opposite direction)
Explanation:
Initially, inductor opposes current rise completely.
MCQ No. 71
If magnetic field in solenoid doubles, energy stored becomes:
a) Double
b) Four times
c) Half
d) Same
Correct answer: b) Four times
Explanation:
Energy ∝ B².
MCQ No. 72
In steady state, energy stored in inductor is:
a) Zero
b) Maximum
c) Infinite
d) Negative
Correct answer: b) Maximum
Explanation:
Current reaches maximum steady value.
MCQ No. 73
An RL circuit with large inductance will have:
a) Fast current rise
b) Slow current rise
c) Instant current
d) No current
Correct answer: b) Slow current rise
Explanation:
Large L → large τ → slow rise.
MCQ No. 74
If resistance increases while L constant, decay of current becomes:
a) Slower
b) Faster
c) Same
d) Infinite
Correct answer: b) Faster
Explanation:
Higher R → smaller τ → faster decay.
MCQ No. 75
Inductor stores energy in form of:
a) Electric field
b) Magnetic field
c) Heat
d) Charge
Correct answer: b) Magnetic field
Explanation:
Energy stored in magnetic field around
🔹 SECTION–D (AC Generator & Transformer – Intermediate Level)
MCQ No. 76
AC generator converts:
a) Electrical energy to mechanical energy
b) Mechanical energy to electrical energy
c) Heat energy to electrical energy
d) Magnetic energy to heat energy
Correct answer: b) Mechanical energy to electrical energy
Explanation:
AC generator works on electromagnetic induction.
MCQ No. 77
In AC generator, slip rings are used to:
a) Reverse current direction
b) Maintain continuous contact
c) Increase voltage
d) Reduce resistance
Correct answer: b) Maintain continuous contact
Explanation:
Slip rings provide continuous connection with rotating coil.
MCQ No. 78
Frequency of AC generator depends on:
a) Coil area
b) Magnetic field
c) Speed of rotation
d) Number of turns
Correct answer: c) Speed of rotation
Explanation:
Frequency f = ω / 2π.
MCQ No. 79
If speed of rotation doubles, induced emf becomes:
a) Same
b) Double
c) Half
d) Four times
Correct answer: b) Double
Explanation:
E₀ = NBAω.
MCQ No. 80
Peak emf of generator is 200 V. RMS value is approximately:
a) 100 V
b) 141 V
c) 200 V
d) 70 V
Correct answer: b) 141 V
Explanation:
Erms = E₀ / √2.
MCQ No. 81
Transformer works on principle of:
a) Self induction
b) Mutual induction
c) Electrostatics
d) Resistance
Correct answer: b) Mutual induction
Explanation:
Changing current in primary induces emf in secondary.
MCQ No. 82
Step-up transformer increases:
a) Current
b) Voltage
c) Resistance
d) Frequency
Correct answer: b) Voltage
Explanation:
Ns > Np → output voltage increases.
MCQ No. 83
In ideal transformer:
a) Energy is lost
b) Output power > Input power
c) Input power = Output power
d) Current is zero
Correct answer: c) Input power = Output power
Explanation:
No energy loss is assumed.
MCQ No. 84
If primary turns are greater than secondary turns, transformer is:
a) Step-up
b) Step-down
c) Isolation
d) Rectifier
Correct answer: b) Step-down
Explanation:
Voltage is proportional to turns.
MCQ No. 85
Transformer efficiency is maximum when:
a) Copper loss = Iron loss
b) Voltage is maximum
c) Current is maximum
d) Frequency is minimum
Correct answer: a) Copper loss = Iron loss
Explanation:
Condition for maximum efficiency.
MCQ No. 86
Eddy current loss can be reduced by using:
a) Thick iron core
b) Laminated core
c) Copper core
d) Solid steel core
Correct answer: b) Laminated core
Explanation:
Lamination increases resistance to circulating currents.
MCQ No. 87
AC generator produces:
a) DC output
b) Pulsating DC
c) Alternating current
d) Constant voltage
Correct answer: c) Alternating current
Explanation:
Rotating coil produces sinusoidal emf.
MCQ No. 88
If number of secondary turns is half of primary turns, transformer is:
a) Step-up
b) Step-down
c) Isolation
d) Power loss
Correct answer: b) Step-down
Explanation:
Voltage decreases when turns decrease.
MCQ No. 89
Frequency of transformer output depends on:
a) Turns ratio
b) Input frequency
c) Current
d) Core size
Correct answer: b) Input frequency
Explanation:
Transformer does not change frequency.
MCQ No. 90
In transformer, energy transfer occurs through:
a) Electric field
b) Magnetic field
c) Radiation
d) Conduction
Correct answer: b) Magnetic field
Explanation:
Mutual magnetic flux links coils.
MCQ No. 91
If AC peak voltage is 170 V, RMS voltage is approximately:
a) 85 V
b) 120 V
c) 240 V
d) 300 V
Correct answer: b) 120 V
Explanation:
Erms = 170 / √2 ≈ 120 V.
MCQ No. 92
If frequency of AC increases, inductive reactance:
a) Decreases
b) Increases
c) Remains same
d) Becomes zero
Correct answer: b) Increases
Explanation:
XL = 2πfL.
MCQ No. 93
In AC circuit, pure inductor phase difference is:
a) 0°
b) 45°
c) 90°
d) 180°
Correct answer: c) 90°
Explanation:
Voltage leads current by 90°.
MCQ No. 94
Magnetic braking in trains works due to:
a) Gravity
b) Eddy currents
c) Friction
d) Voltage drop
Correct answer: b) Eddy currents
Explanation:
Induced currents produce opposing magnetic force.
MCQ No. 95
If magnetic field is constant, AC generator induced emf is:
a) Zero
b) Maximum
c) Constant
d) Infinite
Correct answer: a) Zero
Explanation:
No change in flux → no emf.
MCQ No. 96
Transformer core is made of silicon steel because:
a) Increases resistance
b) Reduces eddy current loss
c) Increases voltage
d) Reduces turns
Correct answer: b) Reduces eddy current loss
Explanation:
Silicon steel has high resistivity.
MCQ No. 97
Slip rings are used in AC generator to:
a) Rectify current
b) Maintain continuous rotation connection
c) Increase frequency
d) Store energy
Correct answer: b) Maintain continuous rotation connection
Explanation:
Slip rings ensure continuous electrical contact.
MCQ No. 98
If angular speed of generator coil doubles, emf becomes:
a) Same
b) Double
c) Half
d) Four times
Correct answer: b) Double
Explanation:
E₀ = NBAω.
MCQ No. 99
In ideal transformer, power factor is assumed:
a) Zero
b) 0.5
c) 1
d) Infinite
Correct answer: c) 1
Explanation:
Ideal transformer has no phase loss.
MCQ No. 100
AC generator output is:
a) Square wave
b) Sinusoidal wave
c) Triangular wave
d) Constant DC
Correct answer: b) Sinusoidal wave
Explanation:
Rotational motion produces sinusoidal emf.
){kind=link}