Magnetism
9th Grade Science · 6 lessons
Start lesson 1
Lessons in this unit
- 1Magnetic Fields and Field LinesA magnetic field is the region where a magnetic material feels a force. Field lines run from north pole to south outside the magnet, never cross, and are closer together where the field is stronger. Both poles attract iron; only two magnets repel.Experiment
- 2ElectromagnetsA current in a wire creates a magnetic field around it. Wind the wire into a coil and the fields add to give a solenoid field like a bar magnet's. Add an iron core, more turns or more current and the electromagnet gets stronger — and it switches off with the current.Experiment
- 3The Motor EffectA current-carrying wire in a magnetic field experiences a force perpendicular to both, given by F = BIL. Fleming's left-hand rule gives the direction. Reverse either the current or the field and the force reverses — this is what turns an electric motor.Experiment
- 4Electromagnetic Induction and GeneratorsMove a conductor through a magnetic field, or change the field through a coil, and a potential difference is induced. Faster motion, more turns and a stronger field all increase it. Every mains power station generates electricity this way, whatever the fuel.Experiment
- 5Transformers and the National GridA transformer changes the potential difference of an alternating supply using two coils on a shared iron core. Stepping voltage up reduces current for the same power, and because power loss in cables is I²R, high-voltage transmission wastes far less energy.Lesson
- 6Earth's Magnetic FieldEarth behaves like a huge bar magnet, generated by convection in its liquid iron outer core. A compass needle aligns with this field, though magnetic north drifts and is not the geographic pole. The field also deflects charged particles from the Sun, producing auroras.Experiment
🖨️
View in ShopGet all 6 Magnetism lessons as PDF
Printable worksheets & answer keys — $4.99