NEETPhysicsDual Nature of Radiation and MatterMCQ+4 / −1
The work functions of Caesium , potassium and Sodium (Na) are and respectively. If incident electromagnetic radiation has an incident energy of , which of these photosensitive surfaces may emit photoelectrons?
- ABoth Na and K
- BK only
- CNa only
- DCs only
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Correct answer: D
Given energy of photon $E=2.20 ~\mathrm{eV}$
Work function of $$\mathrm{Cs} ~\phi_{0}=2.14 ~\mathrm{eV}, \mathrm{K} ~\phi_{0}=2.30 ~\mathrm{eV}, \mathrm{Na} ~\phi_{0}=2.75 ~\mathrm{eV}$$
We know that $e^{-}$ emitts when $h v>\phi_{0}$
here it is clear that energy of photon is more than the work function of $\mathrm{Cs}$ [Caesium] only so Ans. only (Cs).
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