A charge moving ______ to the direction of the magnetic field does no…

The correct answer is Option (3) → (A) and (C) only

The magnetic Lorentz force on a moving charge is \( \vec{F} = q(\vec{v} \times \vec{B}) \), with magnitude

    \( \displaystyle F = qvB\sin\theta \)

where \( \theta \) is the angle between \( \vec{v} \) and \( \vec{B} \). The force is zero only when \( \sin\theta = 0 \), that is for \( \theta = 0^\circ \) or \( 180^\circ \).

(A) parallel — Correct. \( \theta = 0^\circ \), \( \sin 0^\circ = 0 \), so \( F = 0 \).

(B) perpendicular — Incorrect. \( \theta = 90^\circ \) gives the largest force, \( F = qvB \).

(C) antiparallel — Correct. \( \theta = 180^\circ \), \( \sin 180^\circ = 0 \), so \( F = 0 \).

(D) at any acute angle — Incorrect. For \( 0^\circ \lt \theta \lt 90^\circ \), \( \sin\theta \ne 0 \), so a force acts.

NCERT (2026-27):
Magnetic Field, Lorentz Force – “… (ii) The magnetic force q [ v × B ] includes a vector product of velocity and magnetic field. The vector product makes the force due to magnetic field vanish (become zero) if velocity and magnetic field are parallel or anti-parallel.”