Q1. [1] § Introduction § 12.2 MAGNETIC FIELD DUE TO A CURRENT-CARRYING CONDUCTOR
Assertion (A) : The deflection of a compass needle placed near a current carrying wire decreases when the magnitude of an electric current in the wire is increased.
Reason (R) : Strength of the magnetic field at a point due to a current carrying conductor increases on increasing the current in the conductor.
- (A) Both (A) and (R) are true and (R) is the correct explanation of (A).
- (B) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
- (C) (A) is true, but (R) is false.
- (D) (A) is false, but (R) is true.
Previously asked in CBSE board exam
2024 31/2/1 Q20
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer
(D) (A) is false, but (R) is true.
The Assertion is false — increasing current increases the deflection of the compass needle, not decreases it. The Reason is true — magnetic field strength increases with increasing current.
Explanation
Examiners expect you to identify that the Assertion directly contradicts what Oersted's experiment shows: greater current → stronger magnetic field → greater deflection of the needle. The Reason is a correct statement of the principle. Option (D) is the only choice where R is true and A is false.
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.