Question

The type of radiation that has the greatest penetrating power through matter is:
a.) $\alpha$
b.) $\gamma$
c.) ${\beta ^ - }$
d.) Visible light.

Answer 1

Hint: For penetration power to be high the particular type of the ray must have the high energy. So here among all the four options we will search for the ray of light having the highest energy because the ray of highest energy will be the ray of having greatest penetration power.

Complete step by step solution:

Firstly, the visible light can’t be the answer, since it is having negligible penetration power and mostly, they are harmless, as they fall in between the IR (infrared) and UV (ultraviolet) rays.
Alpha rays are the positively charged particles. These particles have the least penetration power and highest ionization power. The direct contact with the body may result in the serious damage to the skin.

Beta are the particles having extremely high energy that are liberated from the inner nucleus. They have higher penetration power than the alpha particles and can travel through the skin with ease. Though the ionisation power of beta rays is low , direct contact with the body should be avoided.

Gamma rays are the result from the high- frequency end of the electromagnetic spectrum that has no mass. They have the highest power of penetration. They are the highest penetrating but least ionising and very difficult to resist them to enter into the body. Gamma rays can travel through thin concrete and thin lead and they carry a large amount of the energy.

Thus, we came to the conclusion of the discussion that the$\gamma$ rays have the highest energy among all the given options, so the penetration power of the $\gamma$ is maximum among all the given options.
Hence option (B) is the correct answer.

Note: $\gamma$ is having the wavelength is less than $3 \times {10^{ - 11}}$m and the frequency of the $\gamma$ -rays is $3 \times {10^9} - 3 \times {10^{20}}$ and the source of the $\gamma$ -rays are from the secondary effect of radioactive decay. As the gamma rays have no mass and it is also not having any electrical charge. Since the gamma rays are the part of the electromagnetic radiation that can travel with the speed of light, that is $3 \times {10^8}$ m/s. Due to the most energetic form of the light rays the gamma rays can be used in cancer diagnosis.