ElectricityDefinitions

Key Definitions

Part of Mains Electricity & Safety · GCSE GCSE Physics revision

This definitions covers Key Definitions within Mains Electricity & Safety for GCSE Physics. Revise Mains Electricity & Safety in Electricity for GCSE Physics with 18 exam-style questions and 30 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 8 of 16 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.

Topic position

Section 8 of 16

Practice

18 questions

Recall

30 flashcards

📖 Key Definitions

Alternating current (AC): Electric current that continuously reverses direction. UK mains: 50 Hz (reverses 50 times per second), 230 V.

Direct current (DC): Electric current that flows in one direction only. Provided by batteries and DC power supplies.

Live wire (brown): Carries the supply voltage to the appliance. Alternates between approximately +325 V and -325 V. Always potentially lethal.

Neutral wire (blue): Completes the circuit back to the supply. At approximately 0 V.

Earth wire (green and yellow): Safety wire connected to the metal casing of appliances. Normally carries no current; provides low-resistance escape path in case of a fault.

Fuse: A thin wire that melts if the current exceeds its rating, breaking the circuit and cutting off the power supply.

Double insulation: Appliances with non-conducting (plastic) outer casings that do not require an earth wire for safety.

Keep building this topic

Read this section alongside the surrounding pages in Mains Electricity & Safety. That gives you the full topic sequence instead of a single isolated revision point.

How It Works: Why AC Peaks at 325 V But We Say 230 V Key Facts Summary Why the Earth Wire Saves Lives UK Mains Supply — Key Facts

Practice Questions for Mains Electricity & Safety

What does AC stand for, and how does it differ from DC?

A. Alternating current; it flows at a higher voltage than DC
B. Alternating current; it repeatedly changes direction, whereas DC flows in one direction only
C. Adapted current; it is produced only by batteries
D. Alternating current; it flows at a constant rate, whereas DC changes direction

1 markfoundation

Explain how a fuse protects an electrical circuit from damage.

2 marksstandard

Quick Recall Flashcards

What is DC?

Direct Current — current flows in one direction only (batteries provide DC)

What is AC?

Alternating Current — current direction reverses constantly (50 times/second in UK)

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How It Works: Why AC Peaks at 325 V But We Say 230 V

Key Facts Summary