JEE Main 2026 — Jan 21, Shift 1 — Physics solution

JEE Main2026Jan 21, Shift 1Physics

A current carrying is placed vertically and a particle of mass m with charge Q is released from rest. The particle moves along the axis of solenoid. If g is acceleration due to gravity then the acceleration (a) of the charged particle will satisfy :

A
a = g
B
a > g
C
a = 0
D
0 < a < g

Solution

Inside a (vertically-oriented) solenoid the magnetic field $B$ is along its axis. The particle starts from rest and falls under gravity, so its velocity $v$ is also along the axis — parallel (or anti-parallel) to $B$ .

The magnetic force $F_{B} = q v \times B = 0$ when $v ∥ B$ . Hence only gravity acts on the particle, giving $a = g$ .

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