The photoelectric effect refers to the emission of electrons from a material when it is exposed to light. This phenomenon provides crucial insights into the wave-particle duality of light and helps us understand the nature of light as both a wave and a particle.

When light shines on a material, it interacts with the electrons present on the surface. The energy of the light is transferred to the electrons, allowing them to overcome the attractive forces holding them in the material and escape. The emitted electrons are known as photoelectrons.

To illustrate this concept, let's consider a metal surface exposed to light. When the frequency of the light exceeds a specific threshold, determined by the material, the photoelectric effect occurs. Electrons near the surface absorb the energy from individual photons and gain sufficient energy to escape. The number of ejected electrons and their kinetic energy depend on the intensity and frequency of the incident light.

The photoelectric effect played a vital role in developing our understanding of the wave-particle duality of light. It demonstrated that light can be viewed as both a continuous wave and a particle-like entity. The existence of a threshold frequency, below which no electrons are emitted regardless of the light intensity, provided evidence for the particle nature of light. This concept challenged the prevailing wave theory of light and contributed to the development of quantum mechanics.