Question

1. To observe the photoelectric effect in a given metal, the work function is measured to be 2.6 eV. If light with 2.28 eV photons shines on this metal, will the photons not be absorbed, i.e. will they pass through the metal?

2. Sketch the typical structure of bands for a metal and for a semiconductor indicating which states are filled. Why do metals show the full rainbow upon thermal emission but semiconductors give off dominantly just one color?

Answer 1

According to photoelectric effect experiment we know that the photons with energies only greater than work function of the metal can emmit freely moving electron from the metal.

Work function for a metal can be defined as the minimum energy required of a photon to emit electron from the metal in photoelectric experiment.

Here the photons are given energy 2.28eV which is less than the work function (2.6eV) of the metal so no electron will be emited.

But when the photon is collided on the metal it is mostly absorbed by the metal causing the metal to heat a little bit. It will not be able to emit electron from the metal but it will be absorbed surely.