⚡ Electricity & Electronics – Module 4
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🔋 Lamp with battery

The simplest circuit consists only of a battery, two wires, and a lamp.

BatteryLampclosed circuit

There is no switch. The positive and negative terminals of the battery are connected through the lamp. The circuit is therefore closed and the lamp lights up.

In this diagram, the lamp is always on because there is no break anywhere in the circuit.

⭐ Knowledge question

Which components belong in this circuit?

🪛 Lamp with switch

A switch is now added. It can open or close the circuit.

BatterySwitchLamp

Switch open – the circuit is broken – lamp off.

⭐ Knowledge question

When does the lamp light up?

↔️ Two-way switching circuit

With a two-way switching circuit, you can control one lamp from two locations .

BatteryLampupper traveller wirelower traveller wireSwitch ASwitch B

Both switches select the same path: lamp on.

When both changeover switches connect the same traveller wire, the circuit is closed. If they select different paths, the circuit is open.

⭐ Knowledge question

What is a two-way switching circuit used for?