MHT CET · Physics · Dual Nature of Matter
Photons of energy \(10 \mathrm{eV}\) are incident on a photosensitive surface of threshold frequency \(2 \times 10^{15} \mathrm{~Hz}\). The kinetic energy in \(\mathrm{eV}\) of the photoelectrons emitted is [Planck's constant \(\mathrm{h}=6.63 \times 10^{34}\) \(\mathrm{Js}]\)
- A \(8.29 \mathrm{eV}\)
- B \(6.5 \mathrm{eV}\)
- C \(4.2 \mathrm{eV}\)
- D \(1.7 \mathrm{eV}\)
Answer & Solution
Correct Answer
(D) \(1.7 \mathrm{eV}\)
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & \text { Energy of photons, } \mathrm{h} v=10 \mathrm{eV} \\ & \text { Threshold frequency }=2 \times 10^{15} \mathrm{~Hz} \\ & \therefore \text { Work function, } \mathrm{W}_0=\mathrm{h} v_0 \\ & =6.63 \times 10^{-34} \times 2 \times 10^{15} \\ & =13.26 \times 10^{-19} \mathrm{~J} \\ & =\frac{13.26 \times 10^{-19}}{1.6 \times 10^{-19}} \mathrm{eV}=8.3 \mathrm{eV} \\ & \mathrm{KE} \text { of electrons }=\mathrm{h} v-\mathrm{W}_0 \\ & =10-8.3=1.7 \mathrm{eV}\end{aligned}\)
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