Question

Which of the following is of shortest wavelength?
A. X-rays
B.$\gamma $-rays
C. Microwaves
D. Radio waves

Answer 1

Hint: This problem is related to the electromagnetic spectrum. We need to know about different electromagnetic waves like X rays,$\gamma $ rays etc. We need to know about the frequencies and wavelengths of different electromagnetic waves and after comparing them we will answer the question.

Complete answer:
There are 8 kinds of electromagnetic waves,if we arrange them in the ascending order of wavelength and in descending order of frequencies then the order is
$\gamma $ rays, X rays, Ultraviolet radiation, visible light, infrared radiation,microwaves,radio waves and long waves. The wavelength and frequency ranges of X rays,$\gamma $ rays,microwaves and radio waves are given below.

Name of the electromagnetic radiation	Wavelength range	Frequency range
$\gamma $ rays	$1\times {{10}^{-14}}-1\times {{10}^{-10}}m$	$3\times {{10}^{22}}-3\times {{10}^{18}}Hz$
X rays	$1\times {{10}^{-11}}-3\times {{10}^{-8}}m$	$3\times {{10}^{19}}-1\times {{10}^{16}}Hz$
Microwaves	\[1\times {{10}^{-3}}-3\times {{10}^{-1}}m\]	$3\times {{10}^{11}}-1\times {{10}^{9}}Hz$
Radio waves	$1\times {{10}^{-1}}-1\times {{10}^{-4}}m$	$3\times {{10}^{9}}-3\times {{10}^{4}}Hz$

From this table we can clearly see that the $\gamma $ rays have the shortest wavelength among them.

So the correct option is B.

Additional information:
Electromagnetic waves are produced by accelerated charges. These waves do not require any material medium for propagation. The directions of variations of electric and magnetic fields are perpendicular to each other and also perpendicular to the direction of propagation. Thus electromagnetic waves are transverse in nature. They travel with the speed of light. The electric field vector is responsible for the optical effects of an electromagnetic wave and therefore it is known as the light vector.

Note:
We can only see the visible light portion of the electromagnetic waves using naked eye. As the wavelength of the electromagnetic waves increases, the frequency decreases. Because all the electromagnetic waves travel with the speed of light in vacuum. So by remembering either the order of wavelengths or the order of frequencies we can answer this question.