Physics · Class 12 · Chapter 11
Dual Nature of Radiation and Matter
11 lessons 90 min 2 simulations
Light that behaves as a wave in interference and diffraction behaves as a stream of particles when it knocks electrons out of a metal. This chapter follows the photoelectric experiments, shows why the wave picture cannot explain them, and builds Einstein's equation Kmax = hν − φ₀ on the idea of the photon. It then turns the argument round: de Broglie gave every moving particle a wavelength λ = h/p.
What the exam asks
NEET asks for Einstein's equation in all its forms, the threshold frequency ν₀ = φ₀/h, the stopping potential eV₀ = Kmax and the slope h/e of the V₀–ν line, how saturation current and stopping potential respond to intensity and to frequency, photon energy and momentum, photons per second from a beam's power, and de Broglie wavelengths. Marks are lost by letting intensity change the stopping potential, by mixing joules and electron volts, and by forgetting that λ = h/p gets smaller as the particle gets heavier or faster.
Lessons
11 lessons · 90 min
1Electron emissionNCERT §11.1, §11.28 min2Discovery of the photoelectric effectNCERT §11.36 min3The photoelectric experimentNCERT §11.4, §11.4.16 min4Saturation current and stopping potentialNCERT §11.4.210 min 1 sim5Threshold frequency and no time lagNCERT §11.4.37 min6Where the wave picture failsNCERT §11.56 min7Einstein's photoelectric equationNCERT §11.611 min 1 sim8The photonNCERT §11.77 min9Matter waves and de BroglieNCERT §11.87 min10How long is a matter wave?NCERT §11.87 min11Chapter reviewMust-know facts, traps and formulas15 min