Question

How can I calculate the wavelength from energy?

Answer 1

To calculate the wavelength, you need to know either the frequency or the energy of the radiation.

Wavelength from frequency

You can find the relation between wavelength and frequency at

http://socratic.org/questions/how-are-wavelength-and-frequency-of-a-wave-related

For example, what is the wavelength of a radio wave with a frequency of
590 kHz?

`fλ = c`

`λ = c/f` = `(2.998 × 10⁸"m·s⁻¹")/(590 × 10³"s⁻¹")` = 508 m

Wavelength from energy

The formula is

`E = (hc)/λ` or `λ = (hc)/E`, where `h` is Planck's constant.

For example, what is the wavelength of a photon that has an energy of
3.36 × 10⁻¹⁹ J?

`λ = (hc)/E = (6.626 × 10⁻³⁴"J·s" × 2.998 × 10⁸"m·s⁻¹")/(3.36 × 10⁻¹⁹"J")` = 5.91 × 10⁻⁷ m =
591 nm