Logic Circuits

Boolean logic appears in the KS3 National Curriculum for Computing, and in most GCSE Computer Science courses. This page is an interactive demonstration of how we can use Boolean logic to create electrical circuits to perform specific tasks.  Each Boolean operator has it's own symbol, as shown below, and the truth values arrive through the wired connections.  Circuits like these are used inside the computer to perform operations such as addition.

Drag the symbols (logic gates) below into the box to complete the circuit.

AND OR NAND NOR EOR NXOR

You can also click/tap a symbol to copy it and then click/tap to paste it into the box.

Two-Way Light Switch

In your house you probably have a light with more than one switch - e.g. landing lights often have switches upstairs and downstairs. Add the correct logic gate to the circuit and see if you can get this light work to work in the same way. You can click on Upstairs and Downstairs switches to change them.

Upstairs
Downstairs
Upstairs
Downstairs

Security Light

You can buy security lights that come on only when it's dark and they sense some movement. Add the correct logic gate to the circuit and see if you can get it to work (you can click on Darkness and Movement to change them).

Darkness
Movement
Darkness
Movement
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