Question

Which of the following has the maximum penetrating power?
A.Alpha particle
B.Proton
C.Gamma particle
D.positron

Answer 1

Hint:
Penetrating power is the power of a particle to penetrate a given substance, be it a sheet of paper or a body of a living organism. Different particles with different wavelengths and frequencies have different penetrating power.

Complete step by step answer:
An alpha particle can be considered as a fast moving packet which contains two protons and two neutrons. Alpha particles have a charge of \[+2\] and they tend to strongly interact with matter. Alpha particles which are produced during alpha decay, could travel only a few inches in air and it can also be easily stopped by using a sheet of paper. And as we know alpha particles are known to be the heaviest and most highly charged of all the nuclear radiations. Without any other external energy input, these characteristics of alpha particles make it less penetrating than the gamma and beta particles. A proton can be defined as a subatomic particle, which has symbol \[{{p}^{+}}\] with a positive electric charge of \[+1e~\] elementary charge and it has a mass somewhat less than that of a neutron. Protons do not have penetrating power.
We know that gamma particles are a penetrating form of electromagnetic radiation which arises from the process of radioactive decay of atomic nuclei. It comprises the shortest wavelength of electromagnetic waves and hence it has the highest energy of photons.
Gamma particles have high ionizing power and are thus biologically hazardous. Because of their high penetration power, they have the potential to damage bone marrow and internal organs. Positron or an antielectron is the equivalent positive part of an electron. And we know that the penetrating property of an electron is less than that of a gamma particle, so the penetrating property of positron is the same.
So the correct answer is option C.

Note:The increasing order of penetration power, alpha particles are the lowest, then beta particles, and then the gamma particles.
We know that protons do not possess penetrating power and a positron is usually unstable and tends to decompose quickly, so the penetrating power of positron is considered to be negligible.