Light of incident frequency three times the threshold frequency is incident on a photo sensitive material. If the incident frequency is made $\left(\frac{1}{3}\right)^{rd}$ and intensity is doubled then photoelectric current will

Question

The difference between threshold wavelengths for two metal surfaces $ A $ and $ B $ having work functions $ \phi_A = 9 \, \text{eV} $ and $ \phi_B = 4.5 \, \text{eV} $ is: \[ \text{(Given: } h c = 1242 \, \text{eV nm)} \]

Answer 1

Step 1: Emission condition
Emission needs $h\nu\gt h\nu_0$, that is $\nu\gt\nu_0$.

Step 2: Apply to the new frequency
The new frequency equals $\nu_0$, exactly at the threshold, so there is no excess energy for ejected electrons.

Step 3: Conclusion
Intensity does not change the photon energy, so no current flows. Option (A) is correct.

Final Answer:
No photoelectric current flows after the frequency is reduced to the threshold value. \[ \boxed{\text{(A) }\text{be zero}} \]

Light of incident frequency three times the threshold frequency is incident on a photo sensitive material. If the incident frequency is made \(\left(\frac{1}{3}\right)^{rd}\) and intensity is doubled then photoelectric current will

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The Correct Option is A

Solution and Explanation

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