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Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter2 Marks
Question
Ultraviolet light is incident on two photosensitive materials having work functions W1 and W2 (W1 > W2). In which case will the kinetic energy of the emitted electrons be greater? Why?
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Answer

From Einstein’s photoelectric equation $\text{h}\nu=\text{W}+\text{E}_\text{K}$
$\text{E}_\text{K}=\text{h}\nu-\text{W}$
Clearly, smaller the work function, greater is the KE. As W1 > W2, KE for metal of work function W2 will be greater.

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