A tram is powered by overhead wire, the wire has alternating voltage of 1000 V RMS, the frequency of the alternating voltage is 50 Hz. The rails are the other wire.
The tram is moving at speed 100 m/s away from the place where the overhead wire and the rails are connected to the electric grid.
Is the frequency of the electricity Doppler-shifted in the tram frame? Is the energy of the electricity reduced proportionally to the reduction of the frequency of the electricity?