Wave-particle Duality

NCERT introduces wave-particle duality as the principle that radiation, and indeed all matter, possesses both wave-like and particle-like properties, with the aspect revealed depending on the nature of the experiment performed. Interference and diffraction expose the wave character, while the photoelectric effect and photon detection expose the particle character; the two descriptions are complementary rather than contradictory. This unified view resolves the apparent conflict the teacher describes. The option calling light purely a wave is wrong because it cannot explain the photoelectric threshold or discrete photon detection. The option calling light purely a particle is wrong because it cannot account for well-established interference fringes. The option about permanently switching to particles is wrong because light does not lose its wave nature after detection; each fresh experiment can again reveal either aspect. As stated in NCERT Class 12, Chapter 11, the wave and particle pictures are complementary faces of the same physical reality. A consistency check confirms that duality accommodates both interference and photon phenomena without contradiction, exactly as the observations demand.