Chapter Exam

Chapter-4 Moving Charges and Magnetism — Online MCQ Test

Q: The Biot-Savart law gives the magnetic field due to which of the following?

Answer: B. A current-carrying conductor — The Biot-Savart law specifically describes the magnetic field produced by a current-carrying conductor or a moving charge.

Q: What is the SI unit of magnetic field strength?

Answer: B. Tesla (T) — Tesla (T) is the SI unit of magnetic field strength or magnetic flux density (B).

Q: The magnetic field inside a long solenoid with n turns per unit length carrying current I is given by:

Answer: B. B = μ₀nI — The magnetic field inside a solenoid is B = μ₀nI, where n is the number of turns per unit length and I is the current.

Q: A rectangular loop ABCD with sides 3 m and 4 m carries current 5 A. It is placed in a uniform magnetic field of 2 T perpendicular to the plane. The torque on the loop is:

Answer: A. Zero — For a rectangular loop in a uniform field perpendicular to its plane, the forces on opposite sides cancel, giving zero net torque.

PHYSICS · Grade 12 · CBSE(NCERT)

Practice Chapter-4 Moving Charges and Magnetism with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 PHYSICS. This chapter covers: Biot-Savart law - Ampere's law - Lorentz force - magnetic field - solenoid - galvanometer - parallel currents. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-4 Moving Charges and Magnetism — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 PHYSICS — Chapter-4 Moving Charges and Magnetism, with answers and explanations. These are sample questions; the exam has its own separate question set.

The Biot-Savart law gives the magnetic field due to which of the following?

A. A stationary point charge
B. A current-carrying conductor ✓
C. A permanent magnet
D. A charged particle at rest

Answer: B. A current-carrying conductor
The Biot-Savart law specifically describes the magnetic field produced by a current-carrying conductor or a moving charge.

What is the SI unit of magnetic field strength?

A. Ampere (A)
B. Tesla (T) ✓
C. Weber (Wb)
D. Henry (H)

Answer: B. Tesla (T)
Tesla (T) is the SI unit of magnetic field strength or magnetic flux density (B).

The magnetic field inside a long solenoid with n turns per unit length carrying current I is given by:

A. B = μ₀I
B. B = μ₀nI ✓
C. B = μ₀I/n
D. B = nI/μ₀

Answer: B. B = μ₀nI
The magnetic field inside a solenoid is B = μ₀nI, where n is the number of turns per unit length and I is the current.

A charged particle moves in a circular path in a uniform magnetic field. The radius of the circular path depends on:

A. Only the charge of the particle
B. Only the magnetic field strength
C. The momentum of the particle and the magnetic field strength ✓
D. Only the velocity of the particle

Answer: C. The momentum of the particle and the magnetic field strength
The radius r = mv/(qB), which depends on the particle's momentum (mv) and the magnetic field strength B.

A rectangular loop ABCD with sides 3 m and 4 m carries current 5 A. It is placed in a uniform magnetic field of 2 T perpendicular to the plane. The torque on the loop is:

A. Zero ✓
B. 60 N·m
C. 120 N·m
D. Cannot be determined without angle information

Answer: A. Zero
For a rectangular loop in a uniform field perpendicular to its plane, the forces on opposite sides cancel, giving zero net torque.