Question

An electron is projected along the axis of a circular conductor carrying current \( I \). The electron will experience

• A. a force at an angle of \( 30^\circ \) with the axis
• B. no force
• C. a force along the axis
• D. a force perpendicular to the axis

Hint:

If velocity and magnetic field are parallel, magnetic force is always zero.

Answer 1

The Correct Option is B

Step 1: Direction of magnetic field.
The magnetic field produced by a circular current-carrying loop along its axis is directed along the axis itself.
Step 2: Direction of velocity of electron.
The electron is projected along the axis, so its velocity vector is parallel to the magnetic field vector.
Step 3: Apply Lorentz force law.
Magnetic force is given by \[ \vec{F} = q(\vec{v} \times \vec{B}) \] Since \( \vec{v} \parallel \vec{B} \), the cross product is zero.
Step 4: Conclusion.
The electron experiences no magnetic force.