question_answer

A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then     AIEEE  Solved  Paper-2005

A) its velocity will decrease

B) its velocity will increase

C) it will turn towards right of direction of motion

D) it will turn towards left of direction of motion

Correct Answer: A

Solution :

When E, v and Bare all along same direction, then magnetic force experienced by electron is zero becausewhile electric force is acting opposite to velocity of electron. So, velocity of electron will decrease.