A photon has energy of 20keV. What are its frequency and wavelength?

So we know that: E = h*(frequency)

but for this equation, we need energy in joules

so since 1eV is 1.6 *

we will multiply the energy in eV to 1.6 * 10^-19

so energy in joules:

20000 * 1.6 * 10^-19

3.2 * j

Now, finding the frequency:

3.2 * 10^-15 = 6.6 * * frequency

frequency = (3.2 * ) / (6.6 * )

frequency = 4.8 * Hz

Finally, finding the wavelength:

we will use a different formula here,

frequency * wavelength = speed of light

wavelength = speed of light / frequency

wavelength = 3 * / 4.8 *

wavelength = 3 * / 4.8

wavelength = 0.625 *

wavelength = 6.25 * m

frequency = 4.8 * Hz