Question

Current $I_o$ flows through the solenoid of length $L$ having $N$ number of turns when its connected to DC. A charged particle is projected along the axis of the solenoid with a speed $v_0$, then the force on the charged particle in the solenoid is:

• A. Becomes zero
• B. Remains same
• C. Decreases
• D. Increases

Answer 1

The correct option is A Becomes zero

Given that,

A charge particle is projected along the axis of the solenoid with a speed v₀.

We know that,

The force acting on a charge particle of charge $q$ moving with a velocity $v$ in a magnetic field $B$.

By the Lorentz force

$F=q(v\times B)$

In a solenoid,

The magnetic field is along the axis of the solenoid and the charge particle projected with velocity $v$ is also along the axis of the solenoid that means $v$ and $B$ are parallel and angle between these vectors is zero.

The magnitude of the force on the charge particle is

$F=q(|v|\times |B|)\sin 0^0$

$F=0$

So, the force is zero.