What are the logic gates in WJEC GCSE Electronics?

The NOT (inverter), AND, OR, NAND, NOR and XOR gates. NOT inverts; AND is 1 only when all inputs are 1; OR is 1 when any input is 1; NAND is AND then NOT; NOR is OR then NOT; XOR is 1 when its two inputs are different. You must know their symbols and truth tables.

What is a truth table?

A truth table lists every combination of the inputs and the resulting output. For n inputs there are 2 to the power n rows. A combinational logic circuit has no memory, so its output depends only on the present inputs and a truth table fully describes it.

What is Boolean algebra used for?

Boolean expressions write logic using a dot for AND, a plus for OR and a bar for NOT. Basic identities such as A dot 1 equals A, A plus A-bar equals 1 and A dot 0 equals 0 let you simplify an expression so the circuit uses fewer gates, making it cheaper, smaller and more reliable.

Why are NAND gates important?

The NAND gate is universal: any logic function can be built from NAND gates alone. A NAND with its inputs joined acts as a NOT gate. This lets a whole circuit be made from one type of chip, simplifying design, stock and testing. NOR gates are universal too.

How is combinational logic examined?

It sits in Component 1 (Discovering Electronics), a 1 hour 30 minute written paper worth 40% of the GCSE. Expect constructing truth tables, identifying or naming gates, writing and simplifying Boolean expressions, building functions from NAND gates, and designing a logic system to meet a requirement using a data sheet to pick the IC.

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WJEC GCSE Electronics: combinational logic systems overview

An overview of the combinational logic content in Component 1 of WJEC Eduqas GCSE Electronics, covering logic levels, the NOT, AND, OR, NAND, NOR and XOR gates, truth tables, Boolean expressions and identities, simplification, NAND universality, and designing a logic system using a data sheet.

Generated by Claude Opus 4.86 min readWJEC Eduqas GCSE Electronics, Component 1Updated 2026-06-15

Reviewed by: AI editorial process; not yet individually human-reviewed

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What the topic covers
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For the official specification

The combinational logic content of WJEC Eduqas GCSE Electronics is the digital heart of Component 1 (Discovering Electronics). It covers logic levels, the logic gates and their truth tables, Boolean algebra and simplification, the universal NAND gate, and designing a logic system. This page maps the content and links to a focused answer page for each part.

What the topic covers

Logic gates and truth tables. Logic levels (1 and 0 as high and low), the NOT, AND, OR, NAND, NOR and XOR gates with their symbols, and constructing truth tables for combinational logic. See Logic gates and truth tables.

Boolean algebra and NAND logic. Boolean expressions and identities, simplifying logic to use fewer gates, building any function from NAND gates, and designing a logic system using a data sheet. See Boolean algebra and NAND logic.

How this content is examined

This content sits in Component 1 (Discovering Electronics), a written paper of 1 hour 30 minutes worth 40% of the GCSE. Expect to construct truth tables, identify and name gates, write and simplify Boolean expressions, build functions from NAND gates, and design a small logic system to a requirement, choosing the IC from a data sheet.

How to study it

Learn every gate's truth table. NOT, AND (0,0,0,1), OR (0,1,1,1), NAND (1,1,1,0), NOR (1,0,0,0), XOR (0,1,1,0).
Read circuits gate by gate. Follow the signal through to build the output truth table or Boolean expression.
Know the Boolean identities. Use them to simplify and cut the gate count.
Remember NAND is universal. Any gate can be built from NANDs; a NAND with joined inputs is a NOT.
Design from the requirement. Turn "when should the output be 1?" into a truth table or expression, simplify, then pick the IC from its data sheet.

For the official specification

WJEC Eduqas publishes the full GCSE Electronics specification, past papers and mark schemes at wjec.co.uk. Always revise from the current specification and the board's own past papers, because question style and the printed equation and symbol lists are board-specific.

Sources & how we know this

WJEC Eduqas GCSE Electronics specification (from 2017) — WJEC Eduqas (2017)