Definition:

The dual nature concept states that radiation (light) and matter can behave both as particles and waves, depending on the situation.

• Combines classical and quantum ideas of physics.

• Developed through experiments in early 20th century.

📌 1️⃣ Wave Nature of Light

• Light behaves as a wave in phenomena like:

  • Interference → bright and dark fringes (double-slit experiment)

  • Diffraction → bending of light around obstacles

  • Polarization → vibration in a single plane

Conclusion: Wave theory explains propagation, superposition, and bending of light.

📌 2️⃣ Particle Nature of Light

• Light behaves as particles called photons in phenomena like:

  • Photoelectric effect → emission of electrons from metal when light shines on it

  • Compton scattering → X-rays scattering from electrons

Key Idea:

• Energy of photon depends on frequency → higher frequency = higher energy

• Supports quantum theory → energy is quantized

📌 3️⃣ Wave Nature of Matter

• Proposed by Louis de Broglie

• All matter particles (like electrons, protons) have wave-like properties

• Wavelength of a particle depends on its momentum

Evidence:

• Electron diffraction → electrons form diffraction patterns when passed through a crystal

• Confirms wave-particle duality for matter

📌 4️⃣ Particle Nature of Matter

• Classical view → matter is made of discrete particles with mass

• Exhibits momentum, kinetic energy, collisions

• Behavior in Newtonian mechanics

📌 5️⃣ Key Experiments

📌 6️⃣ Applications

• Photoelectric effect → solar cells, photodiodes

• Electron microscopy → wave nature of electrons gives high resolution

• Quantum devices → lasers, semiconductors

• Nanotechnology → behavior of electrons as waves

🌟 Quick Notes for Revision

1. Light and matter both exhibit wave and particle properties

2. Wave phenomena → interference, diffraction, polarization

3. Particle phenomena → photoelectric effect, momentum, collisions

4. Dual nature is the foundation of Quantum Mechanics

5. Experiments: Young’s double slit, Photoelectric effect, Electron diffraction