Answer:
7.5x10-^8m
Step-by-step explanation:
the formulae is v=fh ,where f is frequency
h is wavelength
hence wavelength=v/f
since the speed of light is 3x10^8
then the wavelength =3 x 10^8/4 x 10^15
=7.5x10^-8m
5.9m questions
7.8m answers