Cambridge IGCSE·Co-ordinated Sciences 0654·Physics Electrical Safety

📋Key knowledge — Electricity Magnetism

Formulas & equations

Ohm's law: V = IR (voltage = current × resistance)
Power: P = IV = I²R = V²/R
Energy: E = IVt = Pt
Series circuit: R_total = R₁ + R₂ + …
Parallel circuit: 1/R_total = 1/R₁ + 1/R₂ + …
Charge: Q = It (coulombs = amperes × seconds)
Transformer: V₁/V₂ = N₁/N₂ (ideal: V₁I₁ = V₂I₂)

Key facts & rules

Current: flow of charge (electrons in metals). Unit: ampere (A). Measured with ammeter (in series).
Voltage (pd): energy transferred per unit charge. Unit: volt (V). Measured with voltmeter (in parallel).
Resistance: opposition to current. Unit: ohm (Ω).
Series circuit: same current everywhere; voltage splits; resistance adds.
Parallel circuit: same voltage across each branch; current splits; total resistance less than smallest.
Direct current (DC): current always in same direction (batteries).
Alternating current (AC): current reverses direction periodically (mains electricity, 50 Hz in UK).
Magnetic field: caused by moving charges/current. Right-hand rule for solenoid.
Motor effect: current-carrying conductor in magnetic field experiences a force (F = BIl).
Electromagnetic induction: moving conductor in magnetic field (or changing flux) induces EMF.
Step-up transformer: more turns on secondary → higher voltage, lower current.
Step-down transformer: fewer turns on secondary → lower voltage, higher current.

IGCSE Physics — Electrical safety

15 Cambridge IGCSE 0654 questions on electrical safety, across all three components.

About electrical safety on IGCSE 0654

Every Cambridge IGCSE Co-ordinated Sciences 0654 question on electrical safety (Electricity & magnetism, Physics), across all three exam components. Theory and alternative-to-practical come with full mark schemes; multiple choice is interactive — click an option to check it.