Answer
See work below.
Work Step by Step
The principle of complementarity states that to fully understand both light and matter, we must use both the wave theory and the particle theory for each. That is, they have both wave and particle properties.
Example for photons: to understand Young’s double-slit interference experiment with light, we must apply wave theory. To understand the photoelectric effect or the Compton effect, we use particle theory.
Example for electrons: to understand electron diffraction, we must apply wave theory. To understand the rest mass energy or charge of an electron, or experiments such as the Compton effect, we use particle theory.
