An 800 kHz radio signal is detected at a point 11 km distant

An 800 kHz radio signal is detected at a point 1.1 km distant from a transmitter tower. The electric field amplitude of the signal at that point is 110 mV/m. Assume that the signal power is radiated uniformly in all directions and that radio waves incident upon the ground are completely absorbed. The magnetic field amplitude of the signal at that point, in nT, is closest to: 0.29 0.51 0.44 0.37 0.22

Solution

Amplitude of magnetic field is

            B = E / c

               = ( 110 x10^-3 V /m ) / ( 3x10⁸ m/s )

               = 0.37 nT