Physics Exam — Circuits, Ohm's Law, Current and Magnetism
Master the three electrical quantities (voltage, current and resistance), Ohm's law (V = I × R), series and parallel circuits, the difference between direct and alternating current, conductors and insulators, magnetism, electromagnets and electrical power.
Physics & Chemistry · Primary & Secondary
V = I × R. Knowing any two quantities gives you the third. A 10 Ω resistor at 5 V draws 0.5 A. This single formula unlocks most circuit problems at secondary level.
Series: same current through all components — one failure stops the circuit. Parallel: same voltage across each branch — one failure leaves the rest running. Household wiring is always parallel.
A wire carrying current generates a magnetic field. Electromagnets (coil + iron core + current) are the heart of electric motors, MRI scanners, maglev trains and hard drives.
"A Year 8 student wonders why Christmas lights all go out when one bulb fails. The exam explains series circuits — and why modern LED strings use parallel wiring instead."
Tricks and techniques to master this topic faster:
Ohm's law triangle: cover the quantity you want (V, I or R) — the remaining two show the formula.
AC vs DC: batteries give DC; the mains socket gives AC (230 V, 50 Hz in Europe).
Good conductors: copper, silver, aluminium. Good insulators: plastic, rubber, glass, dry wood.
Power formula: P = V × I. A 230 V, 0.26 A bulb consumes ≈ 60 W.
If you are studying Electricity and Magnetism, these curriculum topics complement each other:
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