A photocathode having a work function of 2.8 eV is illuminated with monochromatic electromagnetic radiation whose photon energy is 4.0 eV.What is the threshold (cutoff)frequency for photoelectron production? (1 eV = 1.60 × 10^-19 J,h = 6.626 × 10^-34 J ∙ s) A)6.8 × 10¹⁴_Hz B)2.9 × 10¹⁴_Hz C)7.7 × 10¹⁴_Hz D)8.6 × 10¹⁴_Hz E)9.7 × 10¹⁴_Hz

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Quizplus · Accepted Answer

The threshold frequency (f₀) is given by the equation f₀ = φ/h, where φ is the work function. Converting the work function from eV to joules: φ = 2.8 eV × 1.60 × 10⁻¹⁹ J/eV = 4.48 × 10⁻¹⁹ J. Then, f₀ = 4.48 × 10⁻¹⁹ J / 6.626 × 10⁻³⁴ J∙s = 6.8 × 10¹⁴ Hz.

A Photocathode Having a Work Function of 2