Physics 5 — Modern Physics

The photoelectric effect — Einstein’s Nobel

continues from lesson 1 — values defined earlier in the course stay live here

Light ejects electrons from metal only if each photon individually carries enough energy to pay the exit fee (the work function W₀). Brighter-but-redder light ejects nothing — intensity doesn't matter, frequency does. That observation killed the pure wave theory:

W_{0} = 3.6 \cdot 10^{-19}

work function of zinc (J)

✓ pass

E_{photon} > W_{0}

can green light free an electron from zinc?

KE_{e} = E_{photon} - W_{0}

1.1056 \times 10^{-20}

leftover energy becomes electron speed (J)