Key observations:
• Instantaneous emission (no time lag)
• Existence of threshold frequency (ν₀)
• Kinetic energy ∝ frequency (not intensity)
• Photocurrent ∝ intensity (for ν > ν₀)

Work function: φ = hν₀ (minimum energy to eject electron).

Maximum KE: K_max = hν – φ = eV_s (stopping potential).

Stopping potential V_s = (h/e)ν – (φ/e).

For electron accelerated through V volts: λ = h/√(2meV) = 12.27/√V Å.

For any particle: λ = h/√(2mK) (K = kinetic energy).

💡 NEET TIPS & SHORTCUTS

• Threshold frequency ν₀ = φ/h; work function φ = hν₀.
• Stopping potential V_s ∝ ν, independent of intensity.
• de Broglie wavelength λ ∝ 1/√V for electrons.
• For same kinetic energy, lighter particle has longer λ.

⚠️ COMMON MISTAKES

• Confusing work function with threshold frequency.
• Using λ = h/(mv) for relativistic particles without correction.
• Assuming photocurrent depends on frequency (it depends on intensity).
• Forgetting that de Broglie waves are probability waves, not physical waves.

Einstein equation: hν = φ + K_max

Stopping potential: eV_s = K_max

Work function: φ = hν₀

Photon momentum: p = h/λ

de Broglie wavelength: λ = h/p

Electron wavelength (V volts): λ = 12.27/√V Å

Uncertainty principle: Δx·Δp ≥ h/4π