Question

The frequency of violet light is about twice that of red light. Compare the energy of violet photon with the energy of a red photon.

Answer 1

For photons,

E = hf

where h is Plancks constant,
f is the frequency (you might also see it referred to as 'nu' or v), so

E(red) = hf
E(vio) = h(2f)

E(vio) / E(red) = 2

So the energy of violet light is twice that of red.

Answer 2

"Modelling of light can be explained by the two theories wave model and particle model.

Both models can be used to describe colour. According to the wave model, colour depends on frequency. Violet light has a higher frequency than red light (about twice).

But according to the particle model, colour depends on energy. A violet photon transfers more energy the red photon (about twice as much). The two models are related to planks equation.

$The\quad energy\quad of\quad red\quad light\quad photon\quad is\quad 1.65\quad -2.00\quad eV$

$The\quad energy\quad of\quad violet\quad light\quad phoon\quad is\quad 2.75\quad -3.26\quad eV$"