How about light bulbs, solar panels, thermocouples, batteries, fuel
cells, and fireflies?

Roy Lewallen, W7EL

Tarmo Tammaru wrote:
Any transducer I can think of offhand converts between mechanical energy and
electrical energy, as for instance a loudspeaker, microphone, mechanical
filter, etc.

As for the impedance of free space, one way to build a stealth aircraft is
to cover it with material that has a resistivity of 377 Ohms/square. Then
there is no reflection

Tam/WB2TT