IP Physics Notes (Upper Secondary, Year 3-4): 15) Electromagnetism

Q: What does IP Physics Notes (Upper Secondary, Year 3-4): 15) Electromagnetism cover?
A: Map current-generated fields, magnetic forces, and the DC motor cycle for integration into IP problem solving.

Quick recap -- Electric currents create magnetic fields, and those fields can push on other currents or moving charges. Use the right-hand grip to sketch fields and Fleming's left hand to predict the resulting forces.

Keep your practice loop tight via our IP Physics tuition hub-it links each topic here to quizzes, diagnostics, and WA-style problem sets.

Magnetic Effect of a Current

• Straight wire: concentric circular field lines; use right-hand grip rule $\text{thumb} = \text{current, curled fingers} = \text{field direction}$.
• Flat coil: field resembles that of a bar magnet; centre behaves like the interior of a solenoid.
• Solenoid: produces a strong, nearly uniform field inside; right-hand grip rule gives poles (thumb points to north when fingers curl with current).
• Field strength increases with higher current, more turns, or inserting soft iron core.

Applications of Current-Produced Fields

• Electric bell: current energises an electromagnet which attracts an armature; contact opens, circuit breaks, spring restores armature, cycle repeats.
• Relays: low-current control coil closes or opens a separate high-current circuit.
• Circuit breaker: surge current magnetises a coil strongly enough to trip a latch, opening the live conductor.