Question

Assertion : Magnetic field can not change kinetic energy of a moving charge.
Reason : Magnetic field can not change velocity vector.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

Magnetic force on moving charge is always perpendicular to its velocity.
$\vec{F}=q\left(\vec{v}\times \vec{B}\right)$
Also, work done by magnetic force on a moving charge is zero.