(A) : A solenoid tend to contract when a current passes through it.
(R) : The magnetic field inside the solenoid is uniform.

Options

A. Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'.
B. Both 'A' and 'R' are true and 'R' is not the correct explanation of 'A'
C. 'A' is true and 'R' is false
D. 'A' is false and 'R' is false

Answer

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

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that "A solenoid tends to contract when a current passes through it."
- When current flows through a solenoid, it creates a magnetic field. The individual loops of wire in the solenoid behave like straight conductors. If the current flows in the same direction through these loops, they will attract each other due to the magnetic force between them. This attraction causes the solenoid to contract.

2. **Understanding the Reason:**
- The reason states that "The magnetic field inside the solenoid is uniform."
- A solenoid generates a uniform magnetic field inside it when it carries a steady current. This uniformity is a characteristic of an ideal solenoid, where the field lines are parallel and evenly spaced.

3. **Evaluating the Truth of Each Statement:**
- The assertion is true because the magnetic forces between the loops cause contraction.
- The reason is also true because the magnetic field inside a solenoid is indeed uniform when current flows through it.

4. **Determining the Relationship Between Assertion and Reason:**
- While both statements are true, the reason does not explain why the solenoid contracts. The contraction is due to the attractive forces between the loops, not directly because the magnetic field is uniform.

5. **Conclusion:**
- Therefore, both the assertion and the reason are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
Both A and R are true, but R is not the correct explanation of A.

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