A photon with frequency 6.0×10^14 Hz has energy E. What is E in joules and in electronvolts? (h = 6.626×10^-34 J·s; 1 eV = 1.602×10^-19 J)

A photon with frequency 6.0×10^14 Hz has energy E. What is E in joules and in electronvolts? (h = 6.626×10^-34 J·s; 1 eV = 1.602×10^-19 J)

• A. E ≈ 1.50×10^-19 J ≈ 0.94 eV
• B. E ≈ 3.98×10^-18 J ≈ 24.8 eV
• C. E ≈ 2.99×10^-19 J ≈ 1.86 eV
• D. E ≈ 3.98×10^-19 J ≈ 2.48 eV

Answer: (D)

Energy of a photon is E = h f, so it scales with frequency. Using h = 6.626×10^-34 J·s and f = 6.0×10^14 Hz gives E = (6.626×10^-34)(6.0×10^14) ≈ 3.9756×10^-19 J, about 3.98×10^-19 J. To convert to electronvolts, divide by 1.602×10^-19 J per eV: E ≈ 3.9756×10^-19 / 1.602×10^-19 ≈ 2.48 eV. So the energy is roughly 3.98×10^-19 J and 2.48 eV. The correct choice lists these values, while the others don’t match the energy corresponding to this frequency.

Energy of a photon is E = h f, so it scales with frequency. Using h = 6.626×10^-34 J·s and f = 6.0×10^14 Hz gives E = (6.626×10^-34)(6.0×10^14) ≈ 3.9756×10^-19 J, about 3.98×10^-19 J. To convert to electronvolts, divide by 1.602×10^-19 J per eV: E ≈ 3.9756×10^-19 / 1.602×10^-19 ≈ 2.48 eV. So the energy is roughly 3.98×10^-19 J and 2.48 eV. The correct choice lists these values, while the others don’t match the energy corresponding to this frequency.