Practice question

**Classical wave theory fails** to explain instant emission, threshold existence, K_max dependence on frequency not intensity, saturation current dependence on intensity. Observations: K_max independent of intensity, exists threshold frequency, emission instantaneous, all explained by photon model E = h f, one photon ejects one electron, energy conservation h f = Φ + K_max. E = h v = 6.63 × 10⁻³⁴ × 8.0 × 10¹⁴ = 5.304 × 10⁻¹⁹ J . E = (5.304 × 10⁻¹⁹/1.6 × 10⁻¹⁹) ≈ 3.315 eV . Kₘₐₓ = E - Φ₀ = 3.315 - 3.0 = 0.315 eV . V₀ = (Kₘₐₓ/e) = 0.315 V . Applying E =