JAMB - Physics (1994 - No. 38)
If light with photon energy 2eV is incident suitably on the surface of a metal with work function 3eV, then
no electron will be emitted
the few electrons emitted will have a maximum kinetic energy of 1eV
the few electrons emitted will have a maximum kinetic energy of 3eV
many electrons will be emitted
Giải thích
An electron can only be emitted if photon energy is equal or greater than work function of the plate