Question

A uniform electric field and a uniform magnetic field are produced, and are pointed in the same direction. An electron is projected with its velocity pointed in the same direction

• A. The electron will turn to its left
• B. The electron velocity will decrease in magnitude
• C. The electron will turn to its right
• D. The electron velocity will increase in magnitude.

Answer 1

The correct option is B The electron velocity will decrease in magnitude

Electromagnetic force on electron will be zero $\overrightarrow{V}\times B=0$

Electrostatic force will be $F_e=-E$ backwaard,Hence electron decelerate and velocity will decrease in magnitude.