Question

A charged particle is released from rest in a region of uniform electric and magnetic fields which are parallel to each other. The particle will move on a

• A. Straight line
• B. Circle
• C. Helix
• D. Cycloid

Answer 1

The correct option is A Straight line

When the particle is released from rest, it starts to move along the fields due to application of electric field.
The magnetic force acting on a moving charged particle is given by

$\overrightarrow{F}=q(\overrightarrow{v}\times \overrightarrow{B})$

Since velocity and magnetic fields are parallel, no magnetic force acts on the particle, hence it continues to move in a straight line along with constant acceleration.