Question

Write the names of waves in the electromagnetic spectrum having the smallest and largest wavelength.

Answer 1

Hint: The electromagnetic waves are produced due to accelerating charge. The accelerating charge produces an oscillating electric field in apace which produces an oscillating magnetic field, which also serves as a host of oscillating electric fields. The electromagnetic waves consist of a series of waves from gamma rays to radio waves.

Complete answer:
 James Clerk Maxwell predicted the existence of electromagnetic waves but only visible light was known as electromagnetic waves. But now the electromagnetic waves include visible light waves, X-rays, gamma rays, radio waves, microwaves, ultraviolet and infrared waves. The classification of electromagnetic waves according to increasing order or frequency or decreasing order of wavelength is called electromagnetic spectrum. This classification is based on how the waves are detected or produced.

(i)Radio waves: Radio waves were produced by the accelerated motion of charges in wires. Radio waves are used in radio and television communication systems. Radio waves have high frequencies of $300$gigahertz ($GHz$) and low frequency of $30$ hertz ($Hz$). The wavelength corresponding to frequency $300GHz$ is $1mm$ (which is shorter than the width of a rice grain); the wavelength corresponding to frequency $30Hz$ is $10,000km$ (which is longer than the radius of earth which is $6400km$).

(ii)Microwaves: Microwaves (also known as short-wavelength radio waves), with frequencies in the gigahertz ($GHz$) range. Microwaves are produced by special vacuum tubes (called klystrons, magnetrons and Gunn diodes). Microwaves are suitable for the radar systems used in aircraft navigation because of their short wavelengths. Microwaves are a form of electromagnetic radiation and the wavelength of microwaves ranges from about one meter to one millimetre.

(iii)Infrared waves: Infrared waves are produced by hot bodies and molecules. The wavelength range of infrared waves is $400$ nanometres $(nm)$ to $1$millimetre (mm).

(iv) Visible rays: It is the most familiar form of electromagnetic waves. It is the part of the electromagnetic spectrum which can be detected by the human eye. The frequency of visible wave ranges from $4\times {{10}^{14}}Hz$ to $7\times {{10}^{14}}Hz$ and the corresponding wavelength is about $700-400nm$.

(v)Ultraviolet rays: It covers wavelengths ranging from about \[4\times {{10}^{-7}}m\left( 400nm \right)\] to\[6\times {{10}^{-10}}m\text{ }\left( 0.6\text{ }nm \right)\]. Ultraviolet (UV) radiation is produced by special lamps and very hot bodies. The sun is an important source of ultraviolet light.

(vi) X-rays: The X-ray region lies beyond the UV region of the electromagnetic spectrum. X-rays have several medical applications. It covers wavelengths from about ${{10}^{-8}}m$ down to ${{10}^{-13}}m$.
(vii) Gamma rays: Gamma rays lies in the upper frequency range of the electromagnetic spectrum and wavelength ranges from \[{{10}^{-10}}m\] to less than ${{10}^{-14}}m$. This high frequency radiation is produced in nuclear reactions and also emitted by radioactive nuclei. Gamma rays are used in medicine to destroy cancer cells.

So the answer is the electromagnetic wave with the shortest wavelength is gamma ray and highest wavelength is Radio wave.

Note:
In the electromagnetic wave, lower wavelength or higher frequency waves have more energy. So gamma rays have the most energy and radio waves have the lowest energy. Electromagnetic waves interact with matter via their electric and magnetic fields which set in oscillation charges present in all matter. The detailed interaction and so the mechanism of absorption, scattering, etc., depend on the wavelength of the electromagnetic wave, and the nature of the atoms and molecules in the medium.