WHAT IS AN ELECTRIC CURRENT?
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As you know from lesson 1, electricity is the flow of electrons. If we can control that movement of electrons, we obtain an electric current. How can we control that flow of electrons? We can do it using, for example, a wire. Let's see how:
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- Inside the wire, we can find copper, which is a good electrical conductor. Conductors can lose electrons very easy, so, inside the copper, there are a lot of "free" electrons.
- Those electrons will jump from one atom to another.
- That movement causes a flow of electrons, that is, an electric current.
- Finally, the electrons reach an electric machine and the machine will transform that electricity into a different type of energy. For example, a washing machine transforms electricity into kinetic energy.
There are 2 types of electric currents: direct (DC) and alternating current (AC).
DIRECT CURRENT
When all the electrons move in the same direction, it is called direct current. It is produced by sources such as batteries and solar panels, and it is used in toys and small gadgets. |
ALTERNING CURRENT
In alternating current, electrons are constantly reversing their direction (about 50 to 60 times a second). Alternating current is the most used type of current because it is easier to transport through power lines than direct current. It is used in most appliances you use at home: fridges, ovens, stoves, washing machines,... |
ELECTROMAGNETISM
We can use electricity to create electromagnets. An electromagnet is a magnet that you can switch on and off.
How can we do it? When electricity flows through a wire, an electromagnetic field is created. You can't see it, but it is there! That magnetic field will be stronger if you wind the wire into a coil around an object made of iron.
Where can we find electromagnets? We can find them in many different machines, such as power stations, electric motors, telephones, speakers, doorbells,...
We can use electricity to create electromagnets. An electromagnet is a magnet that you can switch on and off.
How can we do it? When electricity flows through a wire, an electromagnetic field is created. You can't see it, but it is there! That magnetic field will be stronger if you wind the wire into a coil around an object made of iron.
Where can we find electromagnets? We can find them in many different machines, such as power stations, electric motors, telephones, speakers, doorbells,...
Time for animations.
On the following video you will see how a generator works.