State three observable phenomena in… | Physics

Question 1 Report

State three observable phenomena in which waves behave like a particle.

Answer

Answer Details

Waves (electromagnetic radiation) behave like particles in the following observable phenomena:

Photoelectric effect - light falling on a metal surface ejects electrons, and the effect depends on the frequency (energy of each photon) rather than the intensity, which is only explicable if light arrives in discrete quanta (photons).
Compton effect (Compton scattering) - when X-rays are scattered by electrons, the scattered radiation has a longer wavelength. This is explained by treating the X-ray as a particle (photon) that collides elastically with the electron, conserving momentum and energy.
Pair production - a high-energy photon passing near a nucleus disappears and produces an electron-positron pair, showing that the photon carries a definite, particle-like quantity of energy and momentum.

(Thermionic emission and the existence of line/emission spectra are also acceptable examples.)

State three observable phenomena in which waves behave like a particle.