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 (v) for different metals, has greater slope for metals with greater work functions.

If both assertion and reason are true and reason is the correct explanation of assertion.

If both assertion and reason are true but reason is not the correct explanation of assertion.

If assertion is true but reason is false.

If both assertion and reason are false.

Solution

If assertion is true but reason is false.

According to photoelectric equation,

eV_s = hv $-$ W

V_s = $(\frac{h}{e}) ν - (\frac{W}{e})$

h = Planck's constant

For V_s versus v graph

slope = $\frac{h}{e}$ = constant

Some More Questions From Dual Nature of Radiation and Matter Chapter

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