Question

An electron is projected parallel to electric and uniform magnetic fields acting simultaneously in the same direction .The electron

• A. gains kinetic energy
• B. loses kinetic energy
• C. moves along circular path
• D. moves along a parabolic path

Answer 1

The correct option is B loses kinetic energy

In the direction of electric field electron loses it's kinetic energy because a force of magnitude qE is applicable on electron in opposite direction of electric field. So, it velocity decreases and kinetic energy decreases. The force on electron due to magnetic field will be zero since angle between $\overrightarrow{V}$ and $\overrightarrow{B}$ is Zero.