Light exhibits a unique dual nature — it behaves both as a wave and a particle, a concept known as wave-particle duality. This means that light can show properties of waves, such as interference and diffraction, and also behave like particles called photons, especially when interacting with matter.

Wave Nature of Light:

Experiments like the double-slit experiment demonstrate that light can interfere and form patterns like ripples on water, showing that it behaves like a wave. This wave behavior explains phenomena such as diffraction, polarization, and refraction.

Particle Nature of Light:

However, in the photoelectric effect — where light knocks electrons off a metal surface — light acts like it is made of individual packets of energy called photons. This effect cannot be explained by wave theory alone and led Einstein to propose that light’s energy is quantized (carried in discrete amounts).

Quantum View:

In quantum mechanics, this duality is fundamental. Light is neither just a wave nor just a particle — it is a quantum object that behaves differently depending on how you observe or measure it. The concept of wave-particle duality also applies to matter, such as electrons, showing that this is a universal principle in quantum physics.

This dual behavior challenges classical physics and is one of the core ideas that led to the development of quantum mechanics.