Circuit diagrams

Circuit diagrams

We don't draw circuit diagrams with colourful pictures of bulbs and buzzers because not everyone can draw well and so, it would start to get difficult working out what's what. Instead, we draw circuit diagrams.

Circuit diagrams use symbols to represent the components in a circuit.

circuit components table

So, instead of drawing a circuit for a torch like this:

Battery correctly connected switch on

…we draw a circuit diagram like this:

Simple series circuit

Short circuits

A short circuit happens when electric currentElectric current is a flow of electric charges (electrons). can flow round a circuit from one terminal of the batteryA battery is two or more electric cells joined together that can produce an electric current when connected to an electric circuit. to the other without passing through any components. In a short circuit, the wire heats up and the battery will go flat.

Short circuit

Circuit challenges

Use Circuit Builder to try:

making the torch circuit
changing the single 1.5 volt cell to a 3 volt battery
adding more bulbs to the circuit

Did you know?

Modern power stations and steam turbines use the same engineering principles that James Watt (1736-1819) applied when he invented the steam engine.
Electricity used at home is metered in 'units' or kilowatt hours (kWh). Each unit is the same as 1,000 watts of electricity used for 1 hour. 1 unit = 1kWh.
Save energy - Boil just enough water for the number of hot drinks you want to make - that way you won't waste energy.
Michael Faraday (1791-1867) is one of the most famous people involved in the discovery and harnessing of electromagnetic force.
What is a watt? Why is it called a watt? It's a unit measuring electric power, named after James Watt (1736-1819).
At Deptford in 1891, electrical engineer Sebastian Ziani de Ferranti (1864-1930) designed and built the first power station and supply network. His basic system is still used around the world.
In 15 minutes, the sun radiates as much energy onto Earth as all the people on the planet during an entire year. Just imagine if we could channel the sun's energy effectively!
In 1771 Luigi Galvani used electricity to make a dead frog's leg jump!
Save energy - Make sure the dishwasher and washing machine are full before you turn them on and use the lower temperature settings.
Fossil fuels won't go on for ever - coal could run out in 250 years.
Benjamin Franklin (1706-1790) developed the first lightning conductor after flying a kite in a thunderstorm. A spectacular but very dangerous experiment!
In the 1780s, Alessandro Volta invented the first battery - all because of Luigi Galvani's experiments with dead frogs.
Thomas Alva Edison 1847-1931 is one of the most successful inventors ever, applying for over 1,300 patents by 1910, mainly to do with electrical or mechanical development.
Michael Faraday (1791-1867) was the first person to create a way of generating a constant current of electricity. His invention led to the power stations we know today.
What is a volt? And why is it called a volt? The volt measures electromotive force. It was named after the Italian inventor Alessandro Volta (1745-1827)
The ampere is named after André-Marie Ampère (1775-1836). He discovered many of the mathematical principles of electromagnetism.
Fossil fuels won't go on for ever - gas could run out in 40 years.
In 1831 Michael Faraday demonstrated electromagnetic force at the the Royal Institution in London, a famous centre for scientific education and research.
Electric shock victims often can't let go of the thing that is passing the electric current into their body. That's because the electricity makes their muscles contract.
An electric eel can produce powerful electric shocks: up to 500 volts and one ampere of current (in other words, 500 watts).
The Italian inventor Alessandro Volta (1745-1827) is best known for his work on electric current.
In 1800 Alessandro Volta built the world's first battery from discs of copper and zinc sandwiched between cardboard moistened with a salty water.
Fossil fuels won't go on for ever - oil could run out in 30 years.
The first turbine engines were designed by Charles Parson (1854-1931). Today turbine engines used to generate electricity are still based on his designs.
All electrical appliances are rated in watts (W) or kilowatts (kW) ( One kilowatt is the same as 1,000 watts). You can use the ratings to compare how much electricity they use.
Save energy - Finished playing on your games console or other equipment? Remember to switch off!
Today we still use words that Benjamin Franklin (1706-1790) introduced: battery, conductor, positive and negative charge, electric shock and electrician.
In August 1887 the London Electric Supply Corporation commissioned Ferranti to build the first power station. Today our electricity supply is still based on the system that Ferranti designed.
High voltage electricity is carried across the country by pylons and 'stepped down' for domestic use at substations. The National Grid supplies electricity all over the country.
Save energy - Don't forget to switch your TV and computer off when you have finished using them.
Save energy - Use energy efficient light bulbs and, when you are leaving a room empty, remember to turn the lights off.

Short circuits

Circuit challenges

Danger

Did you know?