A photocathode has a work function of 2.8 eV.The photocathode is illuminated with monochromatic radiation whose photon energy is 4.0 eV.The threshold frequency for photoelectron production is closest to: A)6.8 × 10¹⁴ Hz B)2.9 × 10¹⁴ Hz C)7.7 × 10¹⁴Hz D)8.6 × 10¹⁴ Hz E)9.7 × 10¹⁴ Hz

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Quizplus · Accepted Answer

The threshold frequency is given by the equation:$$hf_0 = \phi$$where:* $h$ is Planck's constant* $f_0$ is the threshold frequency* $\phi$ is the work functionSubstituting the given values into the equation, we get:$$(6.626 imes 10^{-34} ext{ J s})(f_0) = (2.8 ext{ eV})(1.602 imes 10^{-19} ext{ J/eV})$$$$f_0 = 2.9 imes 10^{14} ext{ Hz}$$Therefore, the threshold frequency is closest to 2.9 × 10¹⁴ Hz.

A Photocathode Has a Work Function of 2