6 Particle Model of Light

Question 1

Einstein

Answer 1

Explained the photoelectric effect based on the idea that light is quantized (I.e. a particle).

• one electron is liberated from the metal surface for every photon absorbed
• in order for electrons to leave the metal a photon must have enough energy to knock it put of its position around the metal nuclei (this explains the threshold frequency required by the metal)
• of the energy of a photon is too low an electron will not be emitted
• the brighter the light, the more photons hit the metal and therefore more electrons are liberated as long as the photons have enough energy

Question 2

Heinrich HERTZ

Answer 2

Observed the photoelectric effect in the latter part of the 19th centre while or working his spark gap generator. He found that it would better in the presence of visible light and even better with UV light.

Question 3

Compton

Answer 3

His experiment confirmed the particle nature of EMR.