Free Faraday's Law MCQs with Answers
48 Faraday's Law MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Faraday's law states that an induced electromotive force equals the rate of change of magnetic flux linkage through a circuit. Questions cover changing field, area, angle or motion, the negative sign associated with Lenz's law, and the distinction between induced emf and the current that may flow in a closed circuit.
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- A. the magnetic flux through it
- B. the rate of change of magnetic flux linkage
- C. the current in it
- D. the resistance of the circuit
Explanation: It is the rate of change that matters, not the flux itself, so a coil sitting in a strong but steady field has no emf induced in it at…
Correct answer: the rate of change of magnetic flux linkage- A. maximum
- B. zero
- C. half the maximum
- D. reversed in direction
Explanation: With the magnet at rest the flux linkage is constant, so its rate of change is zero and no emf is induced however strong the magnet.
Correct answer: zero- A. induces an emf in a neighbouring coil
- B. opposes any change in the current flowing through itself
- C. stores charge like a capacitor
- D. converts alternating current to direct current
Explanation: A changing current changes the coil's own flux, which by Lenz's law induces a back emf opposing that change, so an inductor resists sudden…
Correct answer: opposes any change in the current flowing through itself- A. henry
- B. weber
- C. tesla
- D. farad
Explanation: One henry is the inductance of a coil in which a current changing at one ampere per second induces a back emf of one volt.
Correct answer: henry- A. perpendicular to the magnetic field
- B. parallel to the magnetic field
- C. at 45 degrees to the field
- D. irrelevant, since the emf is constant
Explanation: The emf depends on the rate of change of flux, not on the flux itself, and that rate is greatest when the coil is edge on to the field…
Correct answer: parallel to the magnetic field- A. Moving the magnet faster
- B. Using a stronger magnet
- C. Increasing the number of turns on the coil
- D. Increasing the resistance of the coil
Explanation: The induced emf depends on flux, turns and speed of change, none of which is altered by the coil's resistance; resistance affects the…
Correct answer: Increasing the resistance of the coil- A. 0.4 V
- B. 0.1 V
- C. 4 V
- D. 2.5 V
Explanation: The motional emf is BvL, that is 0.2 multiplied by 4 multiplied by 0.5, giving 0.4 V.
Correct answer: 0.4 V- A. Battery
- B. Capacitor
- C. Dynamo
- D. Transformer
Explanation: An electric motor and a dynamo are reversible electromagnetic machines: a motor converts electrical energy into mechanical energy, while a…
Correct answer: Dynamo- A. Zero
- B. Maximum
- C. Minimum
- D. Optimum
Explanation: Back emf is produced when the motor rotates and its armature cuts magnetic flux.
Correct answer: Zero- A. zero
- B. 5 H
- C. 5000 H
- D. 5 mH
Explanation: The self-induced emf has magnitude E = L|ΔI/Δt|. Here |ΔI| = |2 A - 3 A| = 1 A and Δt = 1 ms = 0.001 s, so |ΔI/Δt| = 1 A ÷ 0.001 s = 1000…
Correct answer: 5 mH- A. 0.5 mH
- B. 0.5H
- C. 2.0H
- D. 8.0H
Explanation: The self-induced emf satisfies ε = L(di/dt), so L = ε/(di/dt) = 2 V/(4 A s^-1) = 0.5 V s A^-1 = 0.5 H.
Correct answer: 0.5H- A. 0
- B. 1
- C. 2
- D. 3
Explanation: An Ac generator consists of two poles i.e is the north pole and south pole of a magnet so that we can have a uniform magnetic field.
Correct answer: 2- A. Coiled rings
- B. Split rings
- C. Slip rings
- D. Solenoid rings
Explanation: Alternating Current Generators consist of an Armature Coil. It has slip rings, which maintains contact between the Armature coil and…
Correct answer: Slip rings- A. 2 H
- B. 0.2 H
- C. 0.002 H
- D. 5 H
- E. 6 H
Explanation: To find the self-inductance L of the coil, we use the formula L = V / (ΔI/Δt), where V is the induced emf, ΔI is the change in current…
Correct answer: 0.2 H- A. 1000 m/s
- B. 500 m/s
- C. 100 m/s
- D. 15000 m/s
- E. 250000 m/s
Explanation: The emf induced in a conductor moving with a velocity 'v' perpendicular to a magnetic field 'B' is given by the equation: emf = BvL where…
Correct answer: 1000 m/s- A. Electric induction
- B. Magnetic induction
- C. Electromagnetic induction
- D. Dipole induction
Explanation: Option C is correct since electromagnetic induction is a process in which a conductor is put in a particular position and the magnetic…
Correct answer: Electromagnetic induction- A. Halves
- B. Triples
- C. Doubles
- D. Remains unchanged
Explanation: According to Faraday's Law of Electromagnetic Induction, the induced electromotive force (EMF) in a coil is equal to the rate of change of…
Correct answer: Doubles- A. Self Induction
- B. Mutual Induction
- C. Motional EMF
- D. Electrostatic potential
Explanation: The correct answer is Motional EMF. When a conductor of length L moves across a magnetic field B, a potential difference appears across…
Correct answer: Motional EMF- A. Increase
- B. Decrease
- C. Becomes Zero
- D. Remains constant
Explanation: When a motor is overloaded, its speed decreases due to the increased load.
Correct answer: Decrease- A. 2.5 V
- B. 0.4 V
- C. 10 V
- D. -10 V
Explanation: To find the induced electromotive force (e.m.f) in a coil when the current is changing, you can use the formula: ε=−L ΔI/Δt Given that the…
Correct answer: -10 VFaraday's Law MCQs: common questions
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