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

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter1 Mark
MCQ
For question two statements are given-one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions front the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion $(A):$ As work function of a material increases by some mechanism, it requires greater energy to excite the electrons from its surface.
Reason $(R):$ A plot of stopping potential $(V,)$ versus frequency $(\upsilon)$ for different metals, has greater slope for metals with greater work functions.
  • A
    Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
  • B
    Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
  • ✓
    $A$ is true but $R$ is false.
  • D
    $A$ is false and $R$ is also false.
✓

Answer

Correct option: C.
$A$ is true but $R$ is false.
As $\text{eV}_\text{s}=\text{h}\upsilon-\text{W}$
$\text{V}_\text{s}=\Big(\frac{\text{h}}{\text{e}}\Big)\upsilon-\Big(\frac{\text{W}}{\text{e}}\Big)$
For $V_s$ versus $\upsilon$ graph,
Slope $=\frac{\text{h}}{\text{e}}=$ constant.

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