How PH-01 Connects to Other NEET Topics

PH-01 (Dual Nature)
        │
        ├──► PH-02 Atoms & Nuclei
        │    • Bohr model: electrons in orbits have de Broglie standing waves
        │    • nλ = 2πr (Bohr's quantisation = de Broglie condition!)
        │    • Energy levels → photon emission (E = hν links both chapters)
        │
        ├──► PH-04 Optics (Wave Nature of Light)
        │    • Young's double slit: wavelength of light → fringe width β = λD/d
        │    • Here: SAME light is a particle (photon) with E = hν
        │    • Wave-particle duality demonstrated in two different phenomena
        │
        ├──► PH-05 Electronic Devices
        │    • Photodiodes use photoelectric effect (p-n junction photocurrent)
        │    • Solar cells: direct application of photon absorption generating carriers
        │    • LED: reverse of photoelectric — electron recombination → photon emission
        │
        ├──► PH-06 Electromagnetic Waves
        │    • Photon IS the quantum of EM radiation
        │    • E = hν; p = hν/c = h/λ — connects EM wave (ν,λ) to photon (E,p)
        │    • Intensity of EM wave = (number of photons/s/area) × hν
        │
        └──► Chemistry — Atomic Structure
             • Photoelectron spectroscopy (XPS) uses photoelectric effect
             • Quantum numbers from Bohr model → de Broglie justification
             • Hydrogen spectrum: Balmer/Lyman series = photon energies = h$\Delta E$

Key linkage to remember: Bohr's quantisation condition L = nh/2π is equivalent to requiring that electron orbits contain a whole number of de Broglie wavelengths (nλ = 2πr). PH-01 literally provides the physical basis for atomic quantisation in PH-02.