Physics - EM Waves Question with Solution | TestHub

A cube of unit volume contains $35\times 10^7$ photons of frequency $10^{15}\mathrm{Hz}$. If the energy of all the photons is viewed as the average energy being contained in the electromagnetic waves within the same volume, then the amplitude of the magnetic field is $\alpha \times 10^{-9}\mathrm{T}$. Taking permeability of free space ${\mu }_0=4\pi \times 10^{-7}\mathrm{Tm}/\mathrm{A}$, Planck's constant $h=6\times 10^{-34}\mathrm{Js}$ and $\pi =\frac{22}{7}$, the value of $\alpha$ is $\_\_\_\_$.