7(b)]
Here k is related to the wave length
l of the wave by the usual
equation
2
k
λ
π
=
(8 8)
 EXAMPLE 8 1
Heinrich Rudolf Hertz
(1857 – 1894) German
physicist who was the
first to broadcast and
receive radio waves He
produced 
electro-
magnetic waves, sent
them through space, and
measured their wave-
length and speed