ELECTRIC FIELDS IN MATTER — Edward Purcell & David Morin
Physics — E&M · em-waves-force-on-charge
Problem
A free proton was at rest at the origin before the wave described by Eq. (9.28) came past. Let the amplitude E0 equal 100 kilovolts/m. Where would you expect to find the proton at time t=1 microsecond? The proton mass is 1.67⋅10−27 kg. Hint: Since the duration of the pulse is only a few nanoseconds, you can neglect the displacement of the proton during the passage of the pulse. Also, if the velocity of the proton is not too large, you may ignore the effect of the magnetic field on its motion. The first thing to calculate is the momentum acquired by the proton during the pulse.