Assertion : When a metallic plate is partially inserted between the plates of a capacitor its capacity increases.
Reason : If conductivity of conducting plate is more, then increase in capacity will be more.

Options

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 correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

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

### Step 1: Understanding the Assertion
The assertion states: "When a metallic plate is partially inserted between the plates of a capacitor, its capacity increases."

**Explanation:**
When a metallic plate is inserted between the plates of a capacitor, it effectively reduces the distance between the plates. The capacitance \( C \) of a parallel plate capacitor is given by the formula:

\[ C = \frac{A \epsilon_0}{d} \]

where:
- \( C \) is the capacitance,
- \( A \) is the area of the plates,
- \( \epsilon_0 \) is the permittivity of free space,
- \( d \) is the separation between the plates.

When a metallic plate is inserted, it reduces the effective distance \( d \) between the plates, which increases the capacitance.

### Step 2: Understanding the Reason
The reason states: "If the conductivity of the conducting plate is more, then the increase in capacity will be more."

**Explanation:**
The capacitance of a capacitor does not depend on the conductivity of the material inserted between the plates. The formula for capacitance when a metallic plate is inserted does not include conductivity as a factor. Therefore, the increase in capacitance is solely due to the reduction in the distance between the capacitor plates, not the conductivity of the inserted plate.

### Conclusion
- The assertion is **true**: inserting a metallic plate increases the capacitance.
- The reason is **false**: the increase in capacitance does not depend on the conductivity of the metallic plate.

### Final Answer
- Assertion: True
- Reason: False

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