Calculate the wavelength of a photon with energy 4.0 × 10⁻¹⁹ J. Use h = 6.63 × 10⁻³⁴ J·s and c = 3.0 × 10⁸ m/s.
A4.97 × 10⁻⁷ m
B4.97 × 10⁻⁷ Hz
C4.97 × 10¹² m
D1.33 × 10⁻⁴⁵ m
Explanation
📌 E = hc/λ, so λ = hc/E = (6.63×10⁻³⁴)(3.0×10⁸)/(4.0×10⁻¹⁹) = 1.989×10⁻²⁵/(4.0×10⁻¹⁹) = 4.97×10⁻⁷ m. That's about 497 nm — blue-green light. Distractor B: wrong unit; C: wrong exponent; D: wrong direction of ratio.