(A) : A spark occur between the poles of a switch when the switch is opened.
(R) : Current flowing in the conductor produces magnetic field.

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 spark occurs between the poles of a switch when the switch is opened.
- This phenomenon typically occurs when the circuit is interrupted, especially if there is an inductive load present. When the switch is opened, the inductor tries to maintain the current flow, which can lead to a high voltage spike, resulting in a spark.

2. **Understanding the Reason**:
- The reason states that current flowing in the conductor produces a magnetic field.
- This is a fundamental principle of electromagnetism. When an electric current flows through a conductor, it generates a magnetic field around it. This can be demonstrated by bringing a magnetic compass near a current-carrying wire, which will show deflection due to the magnetic field.

3. **Evaluating the Truth of Each Statement**:
- Both the assertion and the reason are true statements:
- The assertion is true because a spark does indeed occur when the switch is opened, especially in circuits with inductors.
- The reason is true as well, since current does produce a magnetic field.

4. **Determining the Relationship**:
- While both statements are true, the reason does not explain the assertion. The spark occurs due to the inductive kickback when the switch is opened, not directly because of the magnetic field produced by the current in the conductor.

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

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