PhotoElectric Effect

Question 1

Define the work function of a metal.

Answer 1

• The minimum energy to remove an electron
• from a metals surface

Question 2

Define the ionisation energy of an atom.

Answer 2

• The minimum energy required to remove an electron
• from the ground state

Question 3

Explain why electrons liberated by the photoelectric effect have a range of kinetic energies up to a maximum value.

Answer 3

• Energy transfered to each electron is the same
• And each electron must overcome the work function (Giving a maximum value)
• However some electrons are deeper than surface level and require more energy to be liberated, hence less kinetic energy.

Question 4

If light was shone on a positivly charged plate, explain why no charge would be lost by the plate. (Photoelectric effect)

Answer 4

• Photoelectric effect causes ejection of negative electrons
• As such the positive charge can only increase on the plate.

Question 5

Explain why electrons are only released in the photoelectric effect above a certain frequency.

Answer 5

• Energy arrives on metal’s surface in discrete packets (Photos)
• Each photon interacts with only 1 electron
• The energy of the photon is dependnt on its frequency
• If E-Photon is greater than the work function of the metal, the electron is liberated