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

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter2 Marks
Question
Ultraviolet light is incident on two photosensitive materials having work functions $W_1$ and $W_2 \ (W_1 > W_2).$ 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 $\text{KE}.$
As $W_1 > W_2, \text{KE}$ for metal of work function $W_2$ will be greater.

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