Question

A charged particle goes undeflected in a region containing an electric and a magnetic field. It is possible that
(a) →E∥→B, →v ∥→E (b) →E is not parallel to →B
(c) →v ∥→B but →E is not parallel to →B (d) →E ∥→B but →v is not parallel to →E

Answer 1

(a) It is possible that E→ || B→, v →|| E→(b) E→ is not parallel to B→

Explanation:

• According to option (a) electric field, velocity and magnetic field are parallel to one another.
• So, there might be the acceleration of the particle, which always go undeflected or continue travelling in the same path.

• There is another possibility that the particle might go undeviated.
• The reason being that the electric force counterbalances the magnetic force.
• So, magnetic field, velocity and electric field lies perpendicular to one another, hence the electric force balances the magnetic force.