NEET (UG)

Practice Test 1 — Moving Charges & Magnetism

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct)

Question 1

The magnetic force on a charge is given by:

Solution: $F = qvB\sin\theta$.

Question 2

A charged particle moving in a magnetic field has constant:

Solution: The field does no work, so speed (and KE) is constant.

Question 3

The radius of a charged particle's circular path in a field is:

Solution: $r = mv/qB$.

Question 4

The field at the centre of a circular loop of $N$ turns is:

Solution: $B = N\mu_0 I/2R$.

Question 5

The field inside a long solenoid is:

Solution: $B = \mu_0 n I$.

Question 6

Two antiparallel currents (opposite directions):

Solution: Opposite currents repel.

Question 7

Ampere's circuital law gives the field most easily for:

Solution: It is practical where symmetry exists.

Question 8

The magnetic moment of a coil of $N$ turns, area $A$, current $I$ is:

Solution: $m = NIA$.

Section B — Assertion & Reason

Question 9

A: A magnetic field cannot change the kinetic energy of a moving charge.
R: The magnetic force is always perpendicular to the velocity of the charge.

Solution: Perpendicular force does no work, so KE is unchanged — R explains A.

Question 10

A: The net force on a current loop placed in a uniform magnetic field is zero.
R: The forces on the opposite sides of the loop are equal and opposite.

Solution: Equal and opposite side-forces cancel, giving zero net force — R explains A.

Question 11

A: Two parallel wires carrying current in the same direction repel each other.
R: Parallel currents in the same direction produce attractive forces.

Solution: Same-direction currents attract, so A is false; R correctly states they attract.

Question 12

A: A radial magnetic field is used in a moving-coil galvanometer.
R: A radial field makes the deflection directly proportional to the current.

Solution: The radial field keeps torque constant per unit current, giving a linear scale — R explains A.