Assertion: Stopping potential depends upon the frequency of incident light but is independent of the intensity of the light.
Reason :The maximum kinetic energy of the photoclectrons is proportional to stopping potential

Options

A. a.If both assertion and reason are ture and reason is the correct explanation of assertion
B. b.If both assertion and reason are true but reason is not the correct explanation of assertion
C. c.If assertion is true but reason is false
D. d.If both assertion and reson are false.

Explanation

To solve the given question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "Stopping potential depends upon the frequency of incident light but is independent of the intensity of the light."

- **Stopping Potential (V_s)**: This is the minimum potential difference needed to stop the most energetic photoelectrons emitted from a material when light is incident on it.
- **Frequency (f)**: According to the photoelectric effect, the energy of the incident photons is given by \( E = hf \), where \( h \) is Planck's constant. The stopping potential is directly related to the energy of the incident photons.
- **Intensity (I)**: This is related to the number of photons hitting the surface per unit time. While increasing intensity increases the number of emitted electrons, it does not affect the maximum kinetic energy of the emitted electrons.

Thus, the assertion is **true**.

### Step 2: Understand the Reason
The reason states that "The maximum kinetic energy of the photoelectrons is proportional to the stopping potential."

- The maximum kinetic energy (\( K_{max} \)) of the emitted photoelectrons can be expressed as:
\[ K_{max} = eV_s \]
where \( e \) is the charge of an electron and \( V_s \) is the stopping potential. This shows that the maximum kinetic energy is indeed proportional to the stopping potential.

Thus, the reason is also **true**.

### Step 3: Analyze the Relationship Between Assertion and Reason
While both the assertion and reason are true, we must determine if the reason correctly explains the assertion. The assertion is about the dependence of stopping potential on frequency and independence from intensity, while the reason discusses the relationship between maximum kinetic energy and stopping potential.

Since the reason does not directly explain why stopping potential depends on frequency and not on intensity, we conclude that the reason, while true, is not a correct explanation of the assertion.

### Final Conclusion
- **Assertion**: True
- **Reason**: True, but not a correct explanation of the assertion.

### Answer
The correct option is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

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