He conceived the
idea 
of 
the 
rotating
magnetic field, which is the
basis of practically all
alternating 
current
machinery, and which
helped usher in the age of
electric power He also
invented among other
things the induction motor,
the polyphase system of ac
power, 
and 
the 
high
frequency induction coil
(the Tesla coil) used in radio
and television sets and
other electronic equipment The SI unit of magnetic field
is named in his honour 7