What is the energy, in electron-volts, of a photon of wavelength 500 nm (h = 6.63 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m/s, e = 1.6 × 10⁻¹⁹ C)?
Correct answer B. 2.49 eV
Explanation
E = hc/λ = (6.63 × 10⁻³⁴ × 3.0 × 10⁸)/(500 × 10⁻⁹) = 3.98 × 10⁻¹⁹ J. Dividing by 1.6 × 10⁻¹⁹ gives 2.49 eV.
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