A current-carrying horizontal aluminium rod is placed between the poles of a horseshoe magnet with the magnetic field directed vertically upward. State the direction of the force on the rod if the current flows from west to east. Name the rule you used.
Generated by claude-sonnet-4-6 · 2026-06-26 01:10 · grounding rag
Model Answer
Current flows from West to East; magnetic field is directed vertically upward.
Applying Fleming's Left-Hand Rule: stretch the forefinger (magnetic field – upward), middle finger (current – west to east), and thumb mutually perpendicular. The thumb points towards the South direction. Therefore, the force on the rod acts towards the South.
Rule used: Fleming's Left-Hand Rule.
Explanation
- Examiners expect two things: (1) the correct direction of force, and (2) the name of the rule — both are needed for full 2 marks.
- Fleming's Left-Hand Rule: forefinger → field, middle finger → current, thumb → force/motion. Always state which finger represents which quantity to show clear understanding.
- Here: Field = up, Current = west→east, so by the rule, force = southward (perpendicular to both).