Electromagnetic Waves

A cube of unit volume contains 35×107 photons of frequency 1015‌Hz. 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 α×10−9T. Taking permeability of free space µ0=4π×10−7‌Tm∕A, Planck's constant h=6×10−34‌Js and π=‌

22

7

, the value of α is ______