Revision: Dual Nature of Matter and Radiation CUET (UG) Dual Nature of Matter and Radiation

It is a phenomenon where light falling on a material (usually a metal) causes it to emit electrons, generally called photoelectrons.

Electrons emitted from the metal during photoelectric emission are called photoelectrons.

The minimum frequency of incident radiation required to just cause photoelectric emission from a given metal is called the threshold frequency.

The emission of electrons from a metal surface when electromagnetic radiation of sufficiently high frequency falls on it. This phenomenon is called the photoelectric effect.

The property by which light or matter can show both wave-like and particle-like behaviour depending on the experiment is called wave-particle duality.

The waves associated with a moving material particle are called matter waves or de Broglie waves.

According to de Broglie, every moving particle is associated with a wave whose wavelength depends on its momentum.

For a particle of momentum p, the associated wavelength is:

For a particle of mass m moving with speed v:

• Photoelectric emission was discovered in 1887 by Heinrich Hertz.
• Hertz made this observation during electromagnetic wave experiments.
• High-voltage sparks across the detector loop were enhanced when the emitter plate was illuminated by ultraviolet light from an arc lamp.
• Light shining on the metal surface facilitated the escape of free, charged particles.
• These free, charged particles are electrons.
• Electrons near the metal surface absorb energy from incident radiation.
• If the absorbed energy is sufficient, electrons overcome the attraction of positive ions in the material.
• The electrons then escape from the metal surface into the surrounding space.

1.  The experiment verified the de-Broglie hypothesis.
2. In this experiment, the wave nature of electron particles was studied with the help of a nickel crystal.
3. Electrons undergo interference and diffraction phenomena and produce alternate bright and dark rings.
4. When accelerating potential V = 54 V:
   λ = 0.165 nm (Experimental value)
   λ = 0.167 nm (Theoretical value from de-Broglie hypothesis)