Q. 20. X-rays can penetrate several metre on a thickness according to its energy, that`s why it is ______.

A. useful

B. harmful

C. both of the above

D. none of the above

Explanation

The x-rays can penetrate several metre on a thickness according to its energy, that`s why it is harmful as well as useful (in medical point of view). As when human body come in contact with a x-ray radiation, it penetrate into the body and destroy the cells of the body at atomic level.

<<<   >>>