Chapter Exam

Chapter-6 Electromagnetic Induction — Online MCQ Test

Q: Which law determines the direction of induced current in a conductor moving through a magnetic field?

Answer: B. Lenz's law — Lenz's law states that the direction of induced current is such that it opposes the change in magnetic flux that produced it.

Q: A rectangular loop is placed in a uniform magnetic field. If the magnetic field is perpendicular to the plane of the loop and remains constant, the induced EMF will be:

Answer: B. Minimum (zero) — Since magnetic flux is constant (uniform field, perpendicular to loop, no change), dΦ/dt = 0, so induced EMF = 0.

PHYSICS · CLASS 12 SECOND PUC · Karnataka State Board

Practice Chapter-6 Electromagnetic Induction with a free chapter-wise online MCQ test for Karnataka State Board CLASS 12 SECOND PUC PHYSICS. This chapter covers: Faraday's laws - Lenz's law - motional EMF - self induction - mutual induction. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-6 Electromagnetic Induction — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 12 SECOND PUC PHYSICS — Chapter-6 Electromagnetic Induction, with answers and explanations. These are sample questions; the exam has its own separate question set.

According to Faraday's law of electromagnetic induction, the induced EMF in a coil is equal to:

A. The rate of change of magnetic flux through the coil ✓
B. The magnetic flux through the coil
C. The resistance of the coil multiplied by current
D. The number of turns multiplied by magnetic field

Answer: A. The rate of change of magnetic flux through the coil
Faraday's law states that induced EMF = -dΦ/dt, which is the negative rate of change of magnetic flux through the coil.

Which law determines the direction of induced current in a conductor moving through a magnetic field?

A. Ohm's law
B. Lenz's law ✓
C. Ampere's law
D. Coulomb's law

Answer: B. Lenz's law
Lenz's law states that the direction of induced current is such that it opposes the change in magnetic flux that produced it.

A rectangular loop is placed in a uniform magnetic field. If the magnetic field is perpendicular to the plane of the loop and remains constant, the induced EMF will be:

A. Maximum
B. Minimum (zero) ✓
C. Increasing with time
D. Equal to BL²

Answer: B. Minimum (zero)
Since magnetic flux is constant (uniform field, perpendicular to loop, no change), dΦ/dt = 0, so induced EMF = 0.

When a magnet falls through a conducting pipe, its acceleration is less than g because:

A. Air resistance opposes motion
B. Induced currents in the pipe create a magnetic field opposing the motion ✓
C. The magnet's weight decreases
D. The pipe exerts a direct magnetic force

Answer: B. Induced currents in the pipe create a magnetic field opposing the motion
As the magnet falls, induced EMF creates currents that produce a magnetic field opposing the change (Lenz's law), creating an upward force.

A rectangular loop with dimensions a×b moves with velocity v perpendicular to a magnetic field B. The motional EMF developed is Bvb (b is the width perpendicular to motion). Which statement is correct about energy considerations?

A. Mechanical work done equals electrical energy dissipated ✓
B. Mechanical work is greater than electrical energy dissipated
C. Electrical energy exceeds mechanical work input
D. No relationship exists between mechanical work and electrical energy

Answer: A. Mechanical work done equals electrical energy dissipated
By energy conservation, mechanical work done against magnetic force equals electrical energy (I²R) dissipated in the loop's resistance.