Frequency of the electromagnetic wave is given as $\mathrm{v}=2 \times 10^{10} \mathrm{~Hz}$
Electric field amplitude is given as $E_{0}=48 \vee \mathrm{m}^{-1}$
Speed of light is known as $c=3 \times 10^{8} \mathrm{~m} / \mathrm{s}$
Energy density of the electric field is represented as,
$U_{E}=\frac{1}{2} \epsilon_{0} E^{2}$
And, energy density of the magnetic field is given as:
$U_{B}=\frac{1}{2 \mu_{0}} B^{2}$
Where,
$\epsilon_{0}$ is the permittivity of free space
$\mu_{0}=$ is the permeability of free space
$E=c B$…(1)
Now,
$c=\frac{1}{\sqrt{\epsilon_{0} \mu_{0}}} . \ldots(2)$
On putting equation (2) in equation (1), we get
$E=\frac{1}{\sqrt{\epsilon_{0} \mu_{0}}} B$
On squaring on both sides, we get
$E^{2}=\frac{1}{\epsilon_{0} \mu_{0}} B^{2}$
$\epsilon_{0} E^{2}=\frac{B^{2}}{\mu_{0}}$
$\frac{1}{2} \epsilon_{0} E^{2}=\frac{1}{2} \frac{B^{2}}{\mu_{0}}$
$\Rightarrow U_{E}=U_{B}$