Question

In a Coolidge tube, the potential difference across the tube is 20 kV, and 10 mA current flows through the voltage supply. Only 0.5 % of the energy carried by the electrons striking the target is converted into X-rays. The X-ray beam carries a power of 

(a) 0.1 W 

(b) 1 W 

(c) 2 W 

(d) 10 W 

Answer 1

Correct Answer is: (b) 1 W 

Power drawn by the Coolidge tube = (20 x 10³ V)(10 x 10^-3 A)

= 200 W.

Power of X-ray beam = 0.5/100 x 200 W = 1 W.