Question

a student observes that shining violet light on a metal surface ejects electrons, while red light does not. how should the student explain this observation using the particle model?
red light photons reflect off the surface, preventing any electrons from being released.
violet light photons have a higher frequency and enough energy to eject electrons.
both light types have the same energy, but red light does not interact with electrons.
red light photons are longer and cause interference, blocking electron movement.

Explanation:

According to the particle model of light (photons), the energy of a photon is given by \(E = h
u\) (where \(h\) is Planck's constant and \(
u\) is the frequency). Violet light has a higher frequency than red light. For the photoelectric effect (electron ejection from a metal surface), the photon must have enough energy (\(E\geq\) work - function of the metal). Since violet light photons have higher frequency (and thus higher energy as \(E\propto
u\)), they can eject electrons. Red light photons have lower frequency (lower energy) and may not have enough energy to overcome the work - function of the metal.

• The first option is incorrect because it's not about reflection preventing electron release. The key is the energy of the photon.
• The second option is correct as it relates the higher frequency (and thus higher energy) of violet light photons to the ability to eject electrons.
• The third option is wrong because red and violet light (with different frequencies) do not have the same energy (\(E = h

u\)).

• The fourth option is incorrect as it's not about the length of photons causing interference for electron movement. The main factor is photon energy.

Answer:

Violet light photons have a higher frequency and enough energy to eject electrons.