13 Quantum Physics

Question 1

Quantum of light

Answer 1

Photon
Einstein called there packets

Question 2

E = hf

Answer 2

Energy = Planck’s constant x frequency

Question 3

Ve = hf

Answer 3

Threshold p.d. x charge on electron = energy of emitted photon

Question 4

W = VQ

Answer 4

Work done = potential difference x charge

Question 5

The photoelectric effect

Answer 5

When high-energy electromagnetic radiation causes electrons to be emitted from metal

Question 6

Key observations of the photoelectric effect

Answer 6

Photons are only emitted if the incident radiation was above the threshold frequency
Increasing intensity does not increase maximum kinetic energy of the photons only the quantity
Emission of photoelectrons is instantaneous

Question 7

Work function

Answer 7

The constant defined for each metal depending on the electrons position relative to the positive ions in the metal

Question 8

hf = phi + KEmax

Answer 8

Energy of a single photon = minimum energy to free a single electron from the metal surface (work function) + maximum kinetic energy of the emitted electron

Question 9

hf0 = phi

Answer 9

Plancks constant x threshold frequency = work function

Question 10

Lambda = h/p

Answer 10

Wavelength = Plancks constant /momentum