Question

If ${{V}_{s}}$​, ${{V}_{x}}$​ and ${{V}_{m}}$ are the speeds of gamma rays, X-rays and microwaves respectively in vacuum, then we can say that,
$\begin{align}
  & A.{{V}_{s}}>{{V}_{x}}>{{V}_{m}} \\
 & B.{{V}_{s}}<{{V}_{x}}<{{V}_{m}} \\
 & C.{{V}_{s}}<{{V}_{x}}>{{V}_{m}} \\
 & D.{{V}_{s}}={{V}_{x}}={{V}_{m}} \\
\end{align}$

Answer 1

Hint: Microwaves, gamma rays, x rays all are included in the category of electromagnetic waves. The magnetic waves are having the same speed if they are in identical mediums. The waves which are travelling in vacuum will be having the speed of the light. Hope these details help you in answering this question.

Complete answer:
Electromagnetic waves do not need a medium to propagate. This is the difference between the mechanical wave and an electromagnetic wave. This concludes that electromagnetic waves can travel through air and solid materials and also travels through the vacuum of space. This is the proof for the explanation for radio waves as a form of light. Here it is mentioned about the microwaves, gamma rays and the x rays. These mentioned waves or rays in the question are in the category of electromagnetic waves. As we all know that magnetic waves have equal speed in similar mediums. Hence we can conclude that the speed of these waves in vacuum are identical to each other and to the speed of light in the vacuum also. Therefore we can write that,
${{V}_{s}}={{V}_{x}}={{V}_{m}}$

The correct answer is given as option D.

Note:
An electromagnetic wave is defined as the wave of the electromagnetic field which is propagating through space by carrying electromagnetic radiant energy. This category of waves consists of radio waves, microwaves, infrared, light, ultraviolet, X-rays, and gamma rays. Electromagnetic waves differ in frequency and wavelength. Electromagnetic waves with larger wavelengths will be having lower frequencies. And also we can say that waves with shorter wavelengths have higher frequencies. Waves with higher frequency have higher amounts of energy. The speed of a wave is calculated as the product of its wavelength and the frequency.