Q1. [2] § 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
When is the force experienced by a current – carrying straight conductor placed in a uniform magnetic field. (1 + 1 = 2)
- (i) Maximum ;
- (ii) Minimum ?
Previously asked in CBSE board exam
2022 31/2/1 Q6 (OR-2)
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
(i) Maximum Force:
The force on a current-carrying conductor placed in a uniform magnetic field is maximum when the direction of current is perpendicular (at right angles) to the direction of the magnetic field.
(ii) Minimum Force:
The force is minimum (zero) when the direction of current is parallel to the direction of the magnetic field.
Source: Chapter 12, Section 12.3
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Explanation
- Examiners expect the key condition stated clearly: 90° → maximum force; 0° (parallel) → minimum/zero force.
- The textbook explicitly states: "the displacement of the rod is largest when the direction of current is at right angles to the direction of the magnetic field."
- For minimum, if current and field are parallel, no force acts — this is the logical counterpart and standard expected answer.
- Use the words "perpendicular" and "parallel" — vague answers lose marks.
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