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Question: Which of the following has the maximum penetrating power? A) Alpha particle B) Proton C) Gam...

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

Explanation

Solution

the radioactive particles or radiation like  α−\text{ }\alpha -particles,  β−\text{ }\beta -particles, and  γ−\text{ }\gamma -particles can penetrate through the material. The penetrating power is the ability to pass through the material. This ability is found to be related to the mass of the radiation. The higher the mass, the lower is the ability to pass through the material.

Complete step by step answer:
The penetrating power of a radioactive particle or radiation is defined as the ability of the radiation to pass through the matter (block of matter).
The more the radiation passes through the matter the greater is the penetrating power of the radiation. Generally, the penetrating power of radiation or radioactive particle depends on the mass of the particle.
We know that the mass of radiation is related to the ionization power. That is, the ability of a particle to interact with matter and destroy matter. But to do so the radiation has to interact with the matter which loses its power to pass through the matter.
We know that there are three common types of radioactive particles viz.  α−\text{ }\alpha - particles,  β−\text{ }\beta - particles, and  γ−\text{ }\gamma - particles.

  1. Alpha particles:
    The  α−\text{ }\alpha -particles are positively charged radiation. It is made up of two protons and two neutrons and thus has an atomic weight of 4 amu units. This has the greatest mass compared to the  β−\text{ }\beta - and  γ−\text{ }\gamma - radiation. We know that the penetrating power is inversely related to the ionization power. That is, penetrating power is inversely related to the mass of radiation. Greater is the mass of particles that lowers its penetrating power. Thus, the  α−\text{ }\alpha -particles have low penetrating power. The alpha particles can be easily blocked by the outside layer of human skin.
  2. Beta particles:
    The  β−\text{ }\beta -particles are the electrons which are obtained from the neutrons of the radioactive nuclei. The  β−\text{ }\beta -particles are negatively charged particles. The mass of electrons is equal to the  12000 amu\text{ }\dfrac{1}{2000}\text{ amu} which is very low when compared to the mass of  α−\text{ }\alpha -particles. Thus, due to less mass, they have higher penetrating power than the alpha particles. The particles can penetrate through the matter which is thick such as paper.
  3. Gamma radiation:
    Let's have a look at the third radioactive particles. The  γ−\text{ }\gamma -particles are electromagnetic radiations. These are part of the electromagnetic spectrum. Gamma radiation has no mass or charge on them. We know that the penetrating power is higher when mass is low. Therefore, gamma radiation has the greatest penetrating power than the  α−\text{ }\alpha - and  β−\text{ }\beta -particles. This radiation can even penetrate through matter such a thick lead or concrete.
    We can write the trend of the penetrating power as follows,
     α-radiation < β-radiation < γ-radiation\text{ }\alpha \text{-radiation }<\text{ }\beta \text{-radiation }<\text{ }\gamma \text{-radiation}

Hence, (C) is the correct option.

Note: The gamma radiation is an electromagnetic radiation. The EMR do not have the mass, as they do not contain the particles. It only possesses the energy which can be explained by the Planck’s equation, E = h !!υ!! \text{ E = h }\\!\\!\upsilon\\!\\!\text{ } where h is Planck's constant. This is harmful to the living cell. These radiations can mutate the cells and cause cancer.