Q1. [1] § 12.2 MAGNETIC FIELD DUE TO A CURRENT-CARRYING CONDUCTOR § 12.2.2 Right-Hand Thumb Rule § 12.3 FORCE ON A CURRENT-CARRYING CONDUCTOR IN A MAGNETIC FIELD
Assertion (A) : A current carrying straight conductor experiences a force when placed perpendicular to the direction of magnetic field.
Reason (R) : The net charge on a current carrying conductor is always zero.
- (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
2023 31/4/1 Q20
Generated by claude-sonnet-4-6 · 2026-06-15 06:49 · grounding rag
Model Answer
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A). The force on a current-carrying conductor in a magnetic field is explained by Fleming's left-hand rule, not by the net charge being zero.
Explanation
- (A) is true: A current-carrying conductor placed perpendicular to a magnetic field experiences maximum force (as stated in section 12.3).
- (R) is true: A current-carrying conductor is electrically neutral overall — the positive lattice ions and drifting negative electrons balance out, so net charge = zero. This is a correct statement.
- However, (R) does not explain (A). The force arises due to the interaction of the magnetic field with the moving charges (current), not because the net charge is zero. Hence option (b) is correct.
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