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

Bihar BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter1 Mark
Question
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.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
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.
✓

Answer

  1. A is true but R is false.

Explanation:

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 Vs versus $\upsilon$ graph,

Slope $=\frac{\text{h}}{\text{e}}=$ constant.

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