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Electron, Photon, Photo-electric Effect and X-Rays — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsElectron, Photon, Photo-electric Effect and X-Rays1 Mark
MCQ
Work function of a metal is $2.51 \mathrm{eV}$. lts threshold frequency is
  • A
    $5.9 \times 10^{14} \mathrm{cycle} / \mathrm{sec}$
  • B
    $6.5 \times 10^{14} \mathrm{cycle} / \mathrm{sec}$
  • C
    $9.4 \times 10^{14} \mathrm{cycle} / \mathrm{sec}$
  • ✓
    $6.08 \times 10^{14} \mathrm{cycle} / \mathrm{sec}$
✓

Answer

Correct option: D.
$6.08 \times 10^{14} \mathrm{cycle} / \mathrm{sec}$
$W_0=h v_0 \Rightarrow v_0= \frac{W_0}{h}=\frac{2.51 \times 1.6 \times 10^{-19}}{6.6 \times 10^{-34}} $
$ =6.08 \times 10^{14} \text { Cycle } / \mathrm{sec} .$

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