Question

Which of the following has the maximum penetrating power?
A. $\alpha -$particle
B. Proton
C. $\gamma -$radiation
D. Positron

Answer 1

Hint: Each type of radiation or particle has a different ability to penetrate materials. The amount of energy which is absorbed depends upon the type of radiation or particle and the type of the absorbing material. We will consider all the given types of particles and radiations to determine the one which has the highest penetrating power.

Complete step by step answer:
Alpha particle is a helium nucleus, which means, two protons and two neutrons. It has a large mass as compared to the other ionising radiations, and possesses a strong positive charge.
Proton is a positively charged particle that resides within the atomic nucleus. Protons are heavy mass subatomic particles.
Gamma rays are high energy electromagnetic waves which are caused by the changes occurring within the nucleus. They have no mass and no charge and travel with the speed of light.
Positron is defined as an antimatter partner of an electron. It has exactly the same mass as the electron but has the opposite electric charge.
Each type of radiation or particle has a different ability to penetrate materials. The material is assumed to have absorbed the radiation. Penetrating power is defined as the power, or say length, of an electron beam which can be transmitted for a particular substance.
The amount of energy which is absorbed depends upon the type of radiation or particle and the type of the absorbing material.
Gamma rays and X-rays are high energy electromagnetic radiation, or, high energy protons. Gamma rays are able to pass through several centimetres of metals and can still be detected on the other side.
Among the given choices, $\gamma -$ radiation has the maximum penetrating power.

So, the correct answer is “Option C”.

Note:
The amount of energy absorbed during penetration of the radiation depends upon the type of radiation or particle and the type of the absorbing material. Students should also remember that the Alpha particles have the least penetrating power among different radiations. They can be stopped by a thick sheet of paper or even a layer of clothes. On the other hand, Gamma rays are the high energy electromagnetic radiation and have the maximum penetration power among different radiations.