Question

Which of the following is not an electromagnetic wave?
A. Light rays
B. X-rays
C. Alpha rays
D. Gamma rays

Answer 1

Recall the different regions of the electromagnetic spectrum and attempt which of the above options is not the part of the electromagnetic spectrum. The electromagnetic waves propagate in the form of photons. One can think of the way in which what is the constituent of the above mentioned rays.

Complete answer:
We know that the electromagnetic waves are created when the vibrating electric charge produces electric and magnetic fields perpendicular to each other. These electromagnetic waves propagate in the form of photons.

To answer this question, let’s check every option one by one as follows,
We know that the light rays are the radiations from the sun and fall within the visible region of the electromagnetic spectrum. These light rays consist of photons traveling in all the directions. Since the light rays are moving photons, we can say that it is an electromagnetic wave. Therefore, the option A is incorrect.

We know that X-rays belong to the electromagnetic spectrum of the radiations. X-rays emit high energy photons which can cause break up of an atom. Therefore, X-ray is an electromagnetic wave. Thus, the option B is incorrect.

We know that the alpha rays are the energetic streams of alpha particles. Alpha particle is a double charged helium atom consisting of two protons and two neutrons. We do not see any photons along with the alpha rays. Therefore, alpha rays cannot be electromagnetic waves.Thus, option C is correct.

We know that the gamma ray is the highest energetic electromagnetic wave. We have seen that the gamma ray is emitted in the radioactive disintegrations. Therefore, the gamma ray is the electromagnetic wave.Thus, the option D is incorrect.

So, the correct answer is option C.

Note: To answer this question, it is crucial to remember the electromagnetic spectrum of radiations. Students should also know that like alpha ray, beta ray is also not the type of electromagnetic wave. For the radiation to be an electromagnetic wave, its radiation must have both electric and magnetic field components.