State Fleming's left-hand rule. Name any two devices that work on the principle of force experienced by a current-carrying conductor in a magnetic field.
Generated by claude-sonnet-4-6 · 2026-06-26 01:10 · grounding rag
Model Answer
Fleming's Left-Hand Rule: Stretch the thumb, forefinger, and middle finger of the left hand so that they are mutually perpendicular. If the forefinger points in the direction of the magnetic field and the middle finger points in the direction of current, then the thumb points in the direction of force (motion) on the conductor.
Two devices based on the force on a current-carrying conductor in a magnetic field:
- Electric motor
- Loudspeaker
Source: Chapter 12, Section 12.3
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Explanation
- Examiners expect the rule stated with all three fingers identified clearly — forefinger = field, middle finger = current, thumb = force/motion. Missing any finger assignment loses marks.
- The source passage explicitly lists "electric motor, electric generator, loudspeakers, microphones and measuring instruments" — pick any two. Electric motor is the safest choice as it is discussed in detail in the chapter.
- This question is typically 3 marks: ~1 mark for each finger's role in the rule (or 2 marks for the complete rule) + 1 mark for naming two devices.