Fiducia TogetherElectricity
Current, voltage, resistance, and the two kinds of circuit.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Current is the rate of flow of charge, in amperes. Potential difference is the energy transferred per unit charge, in volts. Resistance opposes current, in ohms. V = IR.
Where it applies
GCSE physics and combined science, with required practicals.
How it works
In series, current is the same everywhere and potential difference is shared. In parallel, potential difference is the same across each branch and current is shared. Adding resistors in parallel DECREASES total resistance, which students find counter-intuitive.
Ammeters go in series, voltmeters in parallel across the component.
How to use it in your work
Learn the series/parallel rules as two lists and check which circuit you have before writing anything.
For a filament lamp, resistance rises with temperature — that is why its I–V graph curves.
Ammeter in series, voltmeter in parallel. Circuit diagram questions test this directly.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams. The subject song runs the topics in order.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Physics Song The GCSE physics specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.