What is the photoelectric effect? - Leaving Cert Physics - Question i - 2005

The photoelectric effect is a phenomenon in physics where electrons are emitted from a material, typically a metal, when it is exposed to light or radiation.

This effect occurs when photons—particles of light—hit the surface of the material and transfer their energy to the electrons. If the energy of the incoming photons is greater than the work function (the minimum energy needed to remove an electron from the surface of the material), the electrons can be ejected from the material.

Mathematically, the energy of the incoming photon can be expressed as:

u$$ where: - $E$ is the energy of the photon, - $h$ is Planck’s constant (approximately $6.626 \times 10^{-34} $ J·s), and - $\nu$ is the frequency of the light. This effect was pivotal in the development of quantum mechanics and shows the particle-like behavior of light.