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JEE Main Electromagnetic Induction — practice questions

Explore 59 free Electromagnetic Induction questions in JEE Main Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Electromagnetic Induction: quick revision

An induced emf depends on the rate of change of magnetic flux linkage. Specify the loop’s area vector before assigning a flux sign. Lenz’s law determines a direction that opposes the change in flux, not simply the existing field.

Key ideas and when to use them

  • $\Phi=BA\cos\theta$ for a uniform field; θ is measured from the area normal.
  • $\mathcal E=-N\,d\Phi/dt$.
  • Self-induction: $\mathcal E=-L\,dI/dt$.

Common mistakes

  • Flux per turn and total flux linkage differ by the number of turns.
  • A constant field can still produce motional emf when the circuit geometry changes.

Three worked examples

Example 1: Flux through each turn of a 50-turn coil changes uniformly by 0.002 Wb in 0.10 s. Find the average emf magnitude.
  1. Multiply the per-turn change by the number of turns.
  2. $|\mathcal E|=50\times0.002/0.10$.

1 V

Example 2: A 0.50 m conducting rod moves at 3 m/s, with rod, velocity and a uniform 0.40 T field mutually perpendicular. Find its motional emf magnitude.
  1. The perpendicular geometry permits $|\mathcal E|=Blv$.
  2. $|\mathcal E|=0.40\times0.50\times3$.

0.60 V

Example 3: Current through a 0.20 H inductor changes uniformly by 6 A in 0.030 s. Find the induced emf magnitude.
  1. Use the magnitude of the current-change rate.
  2. $|\mathcal E|=0.20\times6/0.030$.

40 V

Qallery AI-assisted study notes and original examples. Further reading: NCERT Physics — Electromagnetic Induction.

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Electromagnetic Induction questions and exercises with answers

Showing questions 1–30 of 59.

Faraday's law of electromagnetic induction states EMF induced equals:Read the answer and worked solution →Lenz's law states the induced current direction is such that it:Read the answer and worked solution →SI unit of magnetic flux is:Read the answer and worked solution →Mutual inductance M between two coils is defined by EMF induced in coil 2:Read the answer and worked solution →Self-inductance L of a coil relates EMF to:Read the answer and worked solution →Energy stored in an inductor of inductance L carrying current I:Read the answer and worked solution →Magnetic flux Φ = B A cos θ. If a coil of area 0.1 m² in B = 0.5 T is rotated from θ=0° to θ=60° in 0.2 s, average EMF:Read the answer and worked solution →A rod of length L moves with velocity v perpendicular to magnetic field B. Motional EMF:Read the answer and worked solution →In a transformer with N₁ = 100 (primary), N₂ = 500 (secondary), if input is 10 V, output is:Read the answer and worked solution →In LR circuit, time constant τ:Read the answer and worked solution →For an ideal inductor in AC circuit at angular frequency ω, inductive reactance:Read the answer and worked solution →For an ideal capacitor in AC, capacitive reactance:Read the answer and worked solution →In an LCR series AC circuit, impedance:Read the answer and worked solution →Resonance in series LCR circuit occurs when:Read the answer and worked solution →RMS value of an AC voltage with peak V₀:Read the answer and worked solution →Average power in AC LCR circuit:Read the answer and worked solution →A 100-turn coil of area 200 cm² is rotated at 50 rev/s in a field of 0.05 T. Peak EMF:Read the answer and worked solution →A solenoid has L = 2 H. Current decreases from 5 A to 1 A in 0.1 s. EMF induced:Read the answer and worked solution →In a step-down transformer with 1000:100 turn ratio (primary:secondary), 220 V input, 1 A secondary current. Primary current (ideal):Read the answer and worked solution →Quality factor Q for series LCR at resonance:Read the answer and worked solution →Two coils with self-inductances L₁ = 4 H, L₂ = 9 H. Maximum possible mutual inductance:Read the answer and worked solution →Energy density of magnetic field B in vacuum:Read the answer and worked solution →In an LR circuit with V = 12 V, R = 4 Ω, L = 2 H, current after t = 0.5 s:Read the answer and worked solution →A capacitor C in series with inductor L (LC circuit) oscillates with frequency:Read the answer and worked solution →In AC circuit with only inductor, average power consumed over one full cycle:Read the answer and worked solution →For an AC generator with EMF ε(t) = ε₀ sin(ωt), the RMS EMF:Read the answer and worked solution →Phase difference between voltage and current in pure capacitor in AC:Read the answer and worked solution →Inductive reactance increases linearly with frequency. At f = 50 Hz, X_L = 100 Ω. At f = 200 Hz, X_L =Read the answer and worked solution →Faraday + Lenz — true or false?Read the answer and worked solution →You push a bar magnet's north pole into a coil wired to a galvanometer. The needle:Read the answer and worked solution →

Worked practice questions

Faraday's law of electromagnetic induction states EMF induced equals:

  1. Current
  2. Rate of change of magnetic flux
  3. Magnetic flux
  4. Charge
Show answer and solution

Correct answer: B. Rate of change of magnetic flux

EMF = -dΦ/dt. The induced EMF in a closed loop equals the negative time-rate of change of magnetic flux through the loop. Negative sign captures Lenz's law (direction).

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Lenz's law states the induced current direction is such that it:

  1. Aids the change in flux
  2. OPPOSES the change in flux that produced it
  3. Has no direction
  4. Flows randomly
Show answer and solution

Correct answer: B. OPPOSES the change in flux that produced it

**Lenz's law:** induced current opposes the change in flux. **Consequence of energy conservation:** if it aided the change, energy would be created from nothing. The minus sign in Faraday's law.

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SI unit of magnetic flux is:

  1. volt
  2. henry
  3. tesla
  4. weber (Wb) = T m²
Show answer and solution

Correct answer: D. weber (Wb) = T m²

Φ_B measured in webers (Wb). We have 1 Wb = 1 T × m². So 1 Wb = 1 V s. Named after Wilhelm Weber.

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