Explanation:
It is known that relation between wavelength and frequency is as follows.
[tex]\lambda = \frac{c}{\nu}[/tex]
where, [tex]\lambda[/tex] = wavelength
c = speed of light = [tex]3 \times 10^{8} m/s[/tex]
[/tex]\nu[/tex] = frequency
It is given that frequency is [tex]7.2 \times 10^{11} s^{-1}[/tex]. Hence, putting this value into the above formula and calculate the wavelength as follows.
[tex]\lambda = \frac{c}{\nu}[/tex]
[tex]\lambda = \frac{3 \times 10^{8} m/s}{7.2 \times 10^{11} s^{-1}}[/tex]
= [tex]0.416 \times 10^{-3} m[/tex]
or, = [tex]4.16 \times 10^{-4} m[/tex]
Thus, we can conclude that wavelength of given radiation is [tex]4.16 \times 10^{-4} m[/tex].