Switches

If there's a gap in the circuitA collection of wires and electric components connected together in such a way that electric current can flow through them., the circuit isn't complete and so, electric current can't flow along the wire. Because no electricity is flowing through the bulb, it doesn't light up.

Try moving your mouse over the picture to see what happens if the circuit is completed.

So, if we want to stop the electric current flowing round a circuit we can disconnect the wire from the batteryA battery is two or more electric cells joined together that can produce an electric current when connected to an electric circuit. or make a gap in the wiring. But there's a better way - we can make a gap in the circuit using a switch.

How do switches work?

Inside a switch there are two strips of metal which are held apart by a spring.

Try moving your mouse over the switch to see how it works.

When the spring pushes the metal strips together so they are touching, we say that the switch is 'closed'. Electric currentElectric current is a flow of electric charges (electrons). can then flow through the switch and around the circuit. When the switch is 'open' the metal strips are pushed apart so the current can't flow.

The best way of making a gap in your circuit to stop current flowing is to put in a switch.

Run your mouse over the picture below to see what happens when we include a switch in the circuit. This is the same circuit you can find inside a torch.

Did you know?

Today we still use words that Benjamin Franklin (1706-1790) introduced: battery, conductor, positive and negative charge, electric shock and electrician.
Modern power stations and steam turbines use the same engineering principles that James Watt (1736-1819) applied when he invented the steam engine.
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.
Michael Faraday (1791-1867) is one of the most famous people involved in the discovery and harnessing of electromagnetic force.
Benjamin Franklin (1706-1790) developed the first lightning conductor after flying a kite in a thunderstorm. A spectacular but very dangerous experiment!
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.
Save energy - Finished playing on your games console or other equipment? Remember to switch off!
Fossil fuels won't go on for ever - oil could run out in 30 years.
The ampere is named after André-Marie Ampère (1775-1836). He discovered many of the mathematical principles of electromagnetism.
In 1831 Michael Faraday demonstrated electromagnetic force at the the Royal Institution in London, a famous centre for scientific education and research.
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.
Save energy - Don't forget to switch your TV and computer off when you have finished using them.
Save energy - Boil just enough water for the number of hot drinks you want to make - that way you won't waste energy.
What is a watt? Why is it called a watt? It's a unit measuring electric power, named after James Watt (1736-1819).
An electric eel can produce powerful electric shocks: up to 500 volts and one ampere of current (in other words, 500 watts).
In 1800 Alessandro Volta built the world's first battery from discs of copper and zinc sandwiched between cardboard moistened with a salty water.
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.
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.
Fossil fuels won't go on for ever - gas could run out in 40 years.
The Italian inventor Alessandro Volta (1745-1827) is best known for his work on electric current.
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.
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 first turbine engines were designed by Charles Parson (1854-1931). Today turbine engines used to generate electricity are still based on his designs.
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.
Save energy - Use energy efficient light bulbs and, when you are leaving a room empty, remember to turn the lights off.
In the 1780s, Alessandro Volta invented the first battery - all because of Luigi Galvani's experiments with dead frogs.
Fossil fuels won't go on for ever - coal could run out in 250 years.
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.
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.

Switches

How do switches work?

Danger

Did you know?