Answer:
So we know that: E = h*(frequency)
but for this equation, we need energy in joules
so since 1eV is 1.6 * [tex]10^{-19}[/tex]
we will multiply the energy in eV to 1.6 * 10^-19
so energy in joules:
20000 * 1.6 * 10^-19
3.2 * [tex]10^{-15}[/tex] j
Now, finding the frequency:
3.2 * 10^-15 = 6.6 * [tex]10^{-34}[/tex] * frequency
frequency = (3.2 * [tex]10^{-15}[/tex]) / (6.6 * [tex]10^{-34}[/tex])
frequency = 4.8 * [tex]10^{18}[/tex] Hz
Finally, finding the wavelength:
we will use a different formula here,
frequency * wavelength = speed of light
wavelength = speed of light / frequency
wavelength = 3 * [tex]10^{8}[/tex] / 4.8 * [tex]10^{18}[/tex]
wavelength = 3 * [tex]10^{-10}[/tex] / 4.8
wavelength = 0.625 * [tex]10^{-10}[/tex]
wavelength = 6.25 * [tex]10^{-11}[/tex] m
frequency = 4.8 * [tex]10^{18}[/tex] Hz
