Question

Which of the following radiations has the least wavelength?

• A. $\gamma -rays$
• B. $\beta -rays$
• C. $\alpha -rays$
• D. $X-rays$

Answer 1

The correct option is A

$\gamma -rays$

Correct Answer: Option A

1. The flow of energy as atomic and subatomic particles and waves is known as radiation.
2. Gamma rays $\left(\gamma -rays\right)$ are electromagnetic radiations emitted from the nucleus due to radioactive decay.
3. Gamma rays have the highest frequency; that is, more waves are emitted per second than any other radiations.
4. This result in them having the shortest wavelength, since $frequency\propto \frac{1}{wavelength}$.
5. The wavelength of gamma rays is in the range ${10}^{-14}m-{10}^{-10}m$.

Incorrect Options:

Option B

1. Beta rays $\left(\beta -rays\right)$ are high-energy and high-speed electrons or positrons emitted due to the radioactive decay of a nucleus.
2. Its frequency is less than that of gamma rays, and therefore wavelength is longer than gamma rays.
3. So, this option is incorrect.

Option C

1. Alpha rays $\left(\alpha -rays\right)$ are the emission of alpha particles that consists of two protons and two neutrons due to the radioactive decay of a nucleus.
2. Its frequency is less than that of gamma rays, and therefore wavelength is longer than gamma rays.
3. So, this option is incorrect.

Option D

1. $X-rays$ are penetrating forms of high-energy electromagnetic radiations.
2. Its frequency is less than that of gamma rays and therefore wavelength is longer than gamma rays.
3. Their wavelength is in the range ${10}^{-10}m-{10}^{-8}m$.
4. So, this option is incorrect.

Hence, option A is correct.