# Electrical Circuit Symbols

Below are some common symbols which represent components that can be found in an electrical circuit.

## Electrical Circuit Components

### Switch

A switch is used to complete or break a circuit.

• Closing a switch completes the circuit
• Opening a switch breaks the circuit

Switches allow us to use devices when we need them and turn them off afterwards.

### Cell

Cells power a circuit by providing the potential difference. This drives the charge that flows around the circuit. They store chemical energy

### Battery

Batteries consist of two or more cells connected in series,

### Diode

A diode allows current to flow in one direction, converting alternating current to direct current. There are different types of diodes.

### Lamp

When energy flows through a lamp, it emits light. This is due to a thin filament that gets heated by the electrical current, which makes it glow.

### Fuse

A fuse is a safety component. It contains a wire with a lower melting point. So if the current gets too high, the wire melts and this breaks the circuit.

Breaking the circuit prevents high currents from causing fires and damaging other components.

### Fixed resistor

Resistors restrict the flow of electric current. A fixed resistor has a resistance that cannot be changed. They are often used to protect sensitive devices from large currents

### Variable resistor

A variable resistor allows you to adjust its resistance. They can be used for dimming lights

### Voltmeter

Voltmeters measure the potential difference across components. They are always placed in parallel to the component being measured.

They must have a high resistance to ensure that hardly any current flows through them

### Ammeter

An ammeter measures the current flowing through a circuit. They are always placed in series with the circuit. An ammeter’s resistance should be very close to zero to avoid affecting the current reading.

### Thermistor

Thermistors are resistors that depend on temperature. As the temperature around a thermistor increases, the resistance of the thermistor decreases.

Thermistors can be used as temperature sensors. They are often found in appliances like fire alarms and thermostats.

### Light-dependent resistor (LDR)

Increasing the light intensity decreases the resistance of a light-dependent resistor.

LDRs are often used in sensors found in cameras, light intensity meters and automatic lighting systems. This makes them useful for burglar alarms.