Question

A magenetic field cannot be used to speed up a charged particle.Give reason

Answer 1

Answer: Look below

Explanation:

When a charged particle move sin a constant magnetic field it experiances a magnetic Lorentz force perpendicular to the direction of velocity of the charged particle due to which it moves in a circular path. When a charge moves in a circular path the magnitude of velocity remains constant while the direction of velocity changes at every instant i.e speed remains constant.

Since speed remains constant and doesn't increase.

ADDITIONAL POINT

Kinetic energy = 1/2 mv^2 also remains constant since both m and v remain constant.

Thus magnetic field cannot speed up a charged particle.

Hope my answer is understandable