1
Q
When monochromatic light is incident on a metal plate, electrons are emitted only when the frequency of the light exceeds a certain threshold frequency. Explain, in terms of energy, why this threshold frequency exists.
A
the energy of each photon/the light increases with frequency (1)
electrons need a minimum amount of energy to leave the metal (1)
this amount of energy is equal to the work function (1)
2
Q
what’s meant by wave particle duality
A
electromagnetic radiation behaves either as a particle or as a wave (1)
