Practice question

**Photon power** light source emits 1.0×10¹⁶ photons/s power 4.0 mW, energy per photon E= P/N =4×10⁻³/10¹⁶=4×10⁻¹⁹ J, wavelength λ= h c/E=6.63×10⁻³⁴×3×10⁸/4×10⁻¹⁹=497 nm, for 6×10¹⁵ photons/s 3.0 mW E=5×10⁻¹⁹ J, for beam 2.5×10¹⁵ photons/s 4×10⁻¹⁹ J each power=10⁻³ W=1 mW, illustrating P = N h f. Energy per photon E = (P/N) = (4.0 × 10⁻³/1.0 × 10¹⁶) = 4.0 × 10⁻¹⁹ J . E = (h c/λ) ⇒ λ = (h c/E) = (6.63 × 10⁻³⁴ × 3 × 10⁸/4.0 × 10⁻¹⁹) ≈ 4.9725 × 10⁻⁷ m = 497.25 nm . Applying E = h f = h c/λ, p = h/λ, K_max = h