Q1. [1] § 12.1 MAGNETIC FIELD AND FIELD LINES
Assertion (A) : The needle of a magnetic compass kept in strong external magnetic field, always aligns itself in north-south direction on the earth.
Reason (R) : Behaviour of the needle of a compass is same as that of a freely suspended bar magnet.
- (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false.
- (D) Assertion (A) is false, but Reason (R) is true.
Previously asked in CBSE board exam
2026 31/5/1 Q32
Generated by claude-sonnet-4-6 · 2026-06-15 06:47 · grounding rag
Model Answer
(D) Assertion (A) is false, but Reason (R) is true.
A compass needle in a strong external magnetic field aligns with that field, not necessarily north-south. Reason (R) is correct — the compass needle behaves like a freely suspended bar magnet.
Explanation
The Assertion is false because a compass needle aligns with the net/dominant magnetic field at its location. Earth's field is weak; a strong external field will deflect the needle away from north-south. The Reason is true as the textbook states the compass needle is itself a small bar magnet, behaving exactly like a freely suspended bar magnet. Since A is false and R is true, option (D) is correct.
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