The wavelength of an electromagnetic wave is related to its frequency and its speed by the following relationship:
[tex]\lambda= \frac{c}{f} [/tex]
where [tex]c=3 \cdot 10^8 m/s[/tex] is the speed of light, while f is the frequency of the wave.
In this problem, [tex]f=1.5 \cdot 10^8 Hz[/tex], therefore the wavelength of the wave is
[tex]\lambda= \frac{3 \cdot 10^8 m/s}{1.5 \cdot 10^8 Hz}=2.0 m [/tex]
