Question

Find the wavelength of electromagnetic waves of frequency $6\times {10}^{12}Hz$ in free space. Give two applications of the type of wave.

Answer 1

Step 1: Given data

Frequency of electromagnetic waves, $f=6\times {10}^{12}Hz$

Step 2: Formula used

Wavelength, $\lambda =\frac{c}{f}$

where $c$ is the speed of the electromagnetic wave and $f$ is the frequency of the electromagnetic wave

Step 3: Calculation

Wavelength,

$$\begin{gathered} \lambda =\frac{c}{f} \\ \Rightarrow \lambda =\frac{3\times {10}^8}{6\times {10}^{12}} \\ \Rightarrow \lambda =5\times {10}^{-5}m \end{gathered}$$
These are infra-red radiations since the wavelength lies between $780\times {10}^{-9}m-1\times {10}^{-3}m$

Applications
(1) It keeps the earth warm.
(2) Infra-red lamps are used to treat muscular strains.

Thus, the wavelength of electromagnetic waves of frequency $6\times {10}^{12}Hz$ in free space is $5\times {10}^{-5}m$.