A radio station broadcasts a signal at a frequency of 800 kHz. at a point 100 km from the transmitter the magnetic field amplitude of the electromagnetic wave from this station is 5.00 * 10^-11 T.
1. the wave length
2. the electric field amplitude
3. the time-averaged energy density of the signal at 100km from the transmitter
4. the time averaged radiation pressure exerted by the signal on absorbing surface at 100 km.