Question

Assertion : As work function of a material increases by some mechanism, it requires greater energy to excite the electrons from its surface.
Reason : A plot of stopping potential (V_s) versus frequency ($\upsilon$) for different metals, has greater slope for metals with greater work functions.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

As $eV_{s}=h\upsilon-W$
$V_{s}=\left(\frac{h}{e}\right)\upsilon-\left(\frac{W}{e}\right)$
For $V_{s}$ versus \upsilon graph, slope = $\frac{h}{e}$ = constant.