Light of incident frequency 3 times the threshold frequency is incident on a photosensitive material. If the incident frequency is made (1/4)th and intensity is tripled then the photoelectric current will ______.
Show Hint
Always check the frequency threshold FIRST! If $f < f_0$, the intensity is completely irrelevant. 10,000 weak photons cannot pool their energy together to do the job of 1 strong photon.
Step 1: Understanding the Concept:
Photoelectric emission only occurs if the incident frequency ($\nu$) is greater than or equal to the threshold frequency ($\nu_0$). Step 2: Formula Application:
Condition for emission: $\nu \geq \nu_0$. Step 3: Explanation:
Initially, $\nu = 3\nu_0$.
New frequency $\nu' = \frac{1}{4} \times \nu = \frac{1}{4} \times (3\nu_0) = 0.75\nu_0$.
Since $0.75\nu_0 < \nu_0$, the incident energy is less than the work function. No photoelectrons will be emitted regardless of the intensity. Step 4: Final Answer:
The photoelectric current will be zero.