Heat at the rate of 200 W is produced in an X-ray tube operating at 20 kV. Find the current in the circuit. Assume that only a small fraction of the kinetic energy of electron is converted into X-rays.

Explanation

`Heat produced//sec=200W `
` rArr (n eV)/t=200 `
` (n e/t)V=200 `
` rArr i=200/V `
` =200/(20xx10^3)=10mA `