All Flashcards
What is the effect of increasing the frequency of light above the threshold frequency in the photoelectric effect?
The kinetic energy of the ejected electrons increases.
What was the effect of Rutherford's gold foil experiment?
It showed that atoms are mostly empty space with a dense, positive nucleus.
What problem did Planck solve by suggesting that light is emitted in discrete packets?
He solved the ultraviolet catastrophe.
Define 'quantum'.
A discrete packet of energy.
What is 'Planck's constant'?
The constant (h) relating energy and frequency, approximately 6.626 x 10^-34 Js.
Define 'photon'.
A particle of light with energy proportional to its frequency.
What is 'threshold frequency'?
The minimum frequency of light required to eject electrons from a metal surface in the photoelectric effect.
Define 'work function'.
The minimum energy required to remove an electron from a solid, also known as binding energy.
What is the 'ultraviolet catastrophe'?
The prediction by classical physics that a blackbody would emit infinite energy at high frequencies.
Describe the photoelectric effect.
Light strikes a metal surface. If the frequency is above the threshold frequency, electrons are ejected. The kinetic energy of ejected electrons increases with the light's frequency.
Outline Rutherford's gold foil experiment.
Alpha particles were directed at gold foil. Most passed through, but some deflected. This indicated a small, dense, positive nucleus.