Question

An X-ray tube is operated at a potential difference of 40 kV, produces heat at the rate of 720 W. Assuming 0.5% of the energy of the incident electrons is converted into X-rays.

Calculate

(a)  the number of electrons per second striking the target

(b)  the velocity of the incident electrons,

Answer 1

(a) As 0.5% of energy is converted into X-ray, therefore heat produced per second at the target is

P = 0.995 VI where I is current inside tube

(b)  Kinetic energy of incident electron  1/2 m v²  = eV