Question

What is the frequency of radiation whose wavelength is 0.80 nm ? express the frequency in inverse seconds to three significant digits?

Answer 1

The relationship between the frequency (f) of an electromagnetic wave, the speed of the wave (which is the speed of light, c) and its wavelength $\lambda$ is given by
$f= \frac{c}{\lambda}$

Since the wavelength of the radiation in the problem is $\lambda= 0.80 nm = 0.80 \cdot 10^{-9} m$, by substituting numbers in the formula we  can get the frequency:
$f= \frac{3 \cdot 10^8 m/s}{0.80 \cdot 10^{-9} m} =3.75 \cdot 10^{17} s^{-1}$