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NEET Electromagnetic Induction and AC: 5 practice MCQs

By the PrepMatic team · Updated 9 Oct 2026 · 4 min read

Electromagnetic Induction and Alternating Currents is where Class 12 Physics turns from static fields to changing ones. Induced emf, inductance, transformers and AC circuits all appear in the NEET paper. The five MCQs below test Faraday's law, self-inductance, a transformer, LC resonance and rms values, at NCERT Class 12 level.

What this chapter covers in the NEET syllabus

The NMC unit is Electromagnetic Induction and Alternating Currents, which covers two NCERT Class 12 chapters. The topics are:

• Magnetic flux, Faraday's law of induction and Lenz's law.
• Motional emf and induced currents, and eddy currents.
• Self-inductance and mutual inductance.
• AC voltage and current, the rms and peak values, and the phase relations in resistive, inductive and capacitive circuits.
• Reactance and impedance of an LCR series circuit, resonance, power in an AC circuit and the power factor.
• The transformer and the AC generator.

Five practice MCQs on EMI and AC

Question 1

A coil of 100 turns experiences a change in magnetic flux through each turn from 0.05 Wb to 0.01 Wb in 0.2 s. The magnitude of the induced emf is:

• A. 2 V
• B. 20 V
• C. 10 V
• D. 25 V

Question 2

The current in a coil of self-inductance 2 H changes uniformly from 3 A to 1 A in 0.1 s. The magnitude of the induced emf is:

• A. 20 V
• B. 80 V
• C. 40 V
• D. 4 V

Question 3

An ideal transformer has 1000 turns in the primary and 50 turns in the secondary. If the primary is connected to a 220 V AC supply, the secondary voltage is:

• A. 11 V
• B. 4400 V
• C. 110 V
• D. 44 V

Question 4

A series LCR circuit has L = 0.1 H and C = 10 μF. The angular frequency at which resonance occurs is:

• A. 100 rad/s
• B. 10⁴ rad/s
• C. 10 rad/s
• D. 1000 rad/s

Question 5

An AC supply is given by e = 220√2 sin(100πt) volts. Its rms voltage and frequency are:

• A. 311 V, 50 Hz
• B. 220 V, 100 Hz
• C. 220 V, 50 Hz
• D. 220√2 V, 100π Hz

Answers and explanations

1. B. Faraday's law gives emf = N(Δφ/Δt). The change in flux per turn is 0.05 − 0.01 = 0.04 Wb, so emf = 100 × 0.04/0.2 = 20 V. Option D comes from using the initial flux alone instead of the change.
2. C. The magnitude of the self-induced emf is L|ΔI/Δt| = 2 × (3 − 1)/0.1 = 2 × 20 = 40 V. The sign (opposing the change) is given by Lenz's law.
3. A. For an ideal transformer Vs/Vp = Ns/Np, so Vs = 220 × 50/1000 = 11 V. This is a step-down transformer, with the voltage reduced and the current correspondingly increased.
4. D. At resonance ω = 1/√(LC) = 1/√(0.1 × 10 × 10⁻⁶) = 1/√(10⁻⁶) = 1/10⁻³ = 1000 rad/s. Resonance frequency is f = ω/2π, about 159 Hz. Check that you are asked for ω, not f.
5. C. Compare with e = e₀ sin ωt: e₀ = 220√2 V and ω = 100π rad/s. The rms value is e₀/√2 = 220 V, and f = ω/2π = 50 Hz. Option A quotes the peak value (311 V) as if it were the rms value.

How to prepare Electromagnetic Induction and AC

• Follow the logic Faraday then Lenz. Faraday's law gives the size of the emf, equal to N times the rate of change of flux, and Lenz's law gives the direction, always opposing the change. Practise predicting the induced current direction in a coil or loop when a magnet moves.
• Be able to work out flux. Flux is B A cos θ. It can change because B changes, the area changes or the angle changes. Spot which one is changing in each question.
• Master motional emf. For a rod of length l moving at speed v perpendicular to B, e = Blv. Combine this with circuit rules to find the force needed to maintain the speed.
• Memorise the AC relations. Vrms = V0/√2, XL = ωL, XC = 1/ωC, Z = √(R² + (XL − XC)²), resonance at ω = 1/√(LC), and power = Vrms Irms cos φ. At resonance Z = R and the power factor is 1.
• Phase pictures. In an inductor current lags voltage by 90°, in a capacitor current leads by 90°, and in a resistor they are in phase.

Spend one session on induction and one on AC, and finish with a mixed set. The overall order for Physics is in the NEET Physics preparation guide, and the full unit list is in the NEET syllabus.

Take a full EMI and AC test on PrepMatic

After your induction and AC revision, take a topic test on PrepMatic (about 15 questions in 30 minutes) and check the result, which applies NEET's negative marking. If you keep your formula notes in a document, you can also upload them and generate a mock from them. The practice hub has more chapters.

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