Ohm's Law
Electrical Science · C&G 2365 Units 202/302 · Free section
Volts push, ohms resist, amps flow: V = I × R captures the relationship, and the classic triangle gives you all three rearrangements. Add the power equations and you can move between watts, volts, amps and ohms from any starting pair.
The trick in exams isn't knowing the formula, it's spotting which quantity hides in the question's units and keeping milliamps and kilohms honest. Our practice questions vary the numbers and the disguises until neither trips you.
This is the foundation of the electrical-science units of the 2365 — series and parallel circuits, and fault-current calculations are all Ohm's law wearing different hats.
Common questions
- Is there a free Ohm's Law quiz?
- Yes. Ohm's Law is taught in the Electrical Science section of TradeTraining, which is free — you can practise in your browser without paying anything.
- Where does Ohm's Law sit in the City & Guilds scheme?
- Ohm's Law maps to C&G 2365 Units 202/302. On TradeTraining it lives in the Electrical Science section as bite-size lessons with practice questions.
- What is Ohm's law in simple terms?
- Ohm's law says the current flowing through a resistance is set by the voltage across it: V = I × R. Know any two of voltage, current and resistance and you can find the third — which is why it underpins nearly every electrical calculation you'll meet.