The Photoelectric Effect

Photon

Packet of energy (a wave, yet acts almost like a particle)

What is the photoelectric effect?

If you shine radiation of high enough frequency onto the surface of a metal, it will instantly emit electrons.

Photoelectric effect diagram

For each 1 photon incident on the metal surface, how many electrons are emitted? What is this interaction called?

1

one-to-one interaction

Work function φ

The minimum energy to release an electron from a metal surface

What will happen if the work function is greater than the energy of a photon?

No electrons will be released

Threshold frequency

The minimum frequency to release an electron from a metal surface

What is the difference between the work function and the threshold frequency?

Work function - metals

Threshold frequency - photons

Intensity

Number of photons / energy of photons

Unit for intensity

Jm^-2s^-2 = Wm^-2

One-to-one interaction

One photon can release one electron

Current

Rate of flow of charge (electrons)

Monochromatic

All photons have the same λ/f/E

Describe what happens if an electron is not on the metal surface

Work is done (energy is used) to bring the electrons to the surface. Then the electron is released but with less E_k than those that were already on the surface, thus demonstrating the (max) in the equation [E_k(max)]

Stopping potential

The potential difference required to stop electrons flowing.

What is the stopping potential based on?

The kinetic energy. The stopping potential is basically just the E_k in eV.

Equation used for stopping potential

E = QV —> V = E/Q