Physics · Grades 9–12
Fields, motors and induced effects · Revision sheet
Connect magnetic fields with currents without treating field lines as wires.
Learn the idea
Field model
Magnetic field lines are a representation of field direction and relative strength, not physical strings.
Current and force
A current-carrying wire can experience a magnetic force; direction depends on current and field.
Induction
Changing magnetic flux through a circuit can induce an emf. A static situation does not automatically do so.
Lenz's law
The induced effect opposes the change that produces it. This is consistent with energy accounting.
Explain without looking
- What information is missing if a question gives only force magnitude but asks its direction on a wire?
- A perpendicular wire length doubles with B and I fixed. If force was 3 N, find the new force.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.