Q. A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. Then the electron will be
A) Be deflected to the left without increase in speed
B) Be deflected to the right without increase in speed
C) Not be deflected but its speed will decrease
D) Not be deflected but its speed will increase
Explanation
(c) As electron is moving parallel to both the fields, so magnetic force does not affect the electron’s motion. But electric force (qE) acts opposite to motion of electron. Hence, electron will not be deflected but its speed decreases.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.