Question

If an electron describes half a revolution in a circle of radius r in a magnetic field B, the energy acquired by it is(a) zero(b) $\frac{1}{2}mv^{2}$(c) $\frac{1}{4}mv^{2}$(d) $\pi r\times B_{ev}$

Answer 1

Answer:

The answer is (a) zero.

Explanation:

• As per rule, the magnetic force is only responsible for changing the direction of electrons while perpendicular to velocity of electrons.

• So, there would be no work done as magnetic force can not accelerate or decelerate electrons.

"Hence, energy acquired by electron will be zero"

Hope this answer may help you