A light wave described by E=60 [ (3 10¹⁵ ) t+ (12 10¹⁵ ) t ] (in SI units) falls on a metal surface of work function 2.8 eV. The maximum kinetic energy of ejected photoelectron is (approximately) _ _ _ _ eV. (h=6.6 10⁻³⁴ ~J . . s. and .e=1.

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A light wave described by E=60 [ (3 10¹⁵ ) t+ (12 10¹⁵ ) t ] (in SI units) falls on a metal surface of work function 2.8 eV. The maximum kinetic energy of ejected photoelectron is (approximately) _ _ _ _ eV. (h=6.6 10⁻³⁴ ~J . . s. and .e=1.6 10⁻¹⁹ C )

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Correct answer: C. 5.1

Light contains two frequencies: ₁ = 3 10¹⁵ rad/s and ₂ = 12 10¹⁵ rad/s For maximum KE, use higher frequency ₂ . Energy: E₂ = h ₂ 2 = 6.6 10⁻³⁴ 12 10¹⁵ 2 = 79.2 10⁻¹⁹ 6.28 = 12.6 10⁻¹⁹ J = 7.9 eV KE_ max = E₂ - = 7.9 - 2.8 = 5.1 eV

A light wave described by E=60 [ (3 10¹⁵ ) t+ (12 10¹⁵ ) t ] (in SI units) falls on a metal surface of work function 2.8 eV. The maximum kinetic energy of ejected photoelectron is (approximately) _ _ _ _ eV. (h=6.6 10⁻³⁴ ~J . . s. and .e=1.6 10⁻¹⁹ C )

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