SACE Stage 2 Physics — Electricity & Magnetism 2.4

Force on a Current-Carrying Conductor

A current-carrying wire placed in a magnetic field experiences a force F = BIℓ sin θ, perpendicular to both the current and the field. Drag to orbit the scene; tilt the wire to see how the force vanishes when it lies parallel to B.

Current direction

Current I

Field strength B

Wire length ℓ

Wire angle θ

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Camera view

F = BIℓ sin θ

sin θ—

|F|—

F direction—

Drag to orbit · scroll to zoom · right-hand rule: fingers from I to B, thumb gives F