Question

What is the energy of a photon with wavelength of 670.8?

Answer 1

The velocity of a wave is calculated by v = λf. From this equation we can take the frequency f = v / λ and substitute in the energy equation to find a new equation for the calculation of the energy from the wavelength: E = hc / λ


To calculate the photon energy, in eV (Electrovolt), when we have the value of the wavelength λ (necessarily given in Å - angstrom), we use an alternative equation given by:
$E = \frac{12400}{\lambda}$

Data: 670.8 Å

Solving:
$E = \frac{12400}{\lambda}$
$E = \frac{12400}{670.8}$
$\boxed{E \approx 18,4eV}$