He
produced 
electro-
magnetic waves, sent
them through space, and
measured their wave-
length and speed He
showed that the nature
of 
their 
vibration,
reflection and refraction
was the same as that of
light and heat waves,
establishing 
their
identity for the first time He 
also 
pioneered
research on discharge of
electricity through gases,
and 
discovered 
the
photoelectric effect HEINRICH RUDOLF HERTZ (1857–1894)
FIGURE 8