Electricity
Lesson 1 How Are Electricity and Magnetism Related?
Electricity
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Have you used electricity in the past hour? Did you turn on a lamp? Did you watch TV? Did you get
something cold to drink from the refrigerator? If you did any of these things, you used electricity.
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You use electricity every day, but do you know what it is? To understand electricity, you have to think
about atoms.
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Recall that atoms contain charged particles.
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A proton has a positive charge.
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An electron has a negative charge.
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An atom can have more electrons than protons.
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This gives the atom a negative charge.
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An atom with more protons than electrons has a positive charge.
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Atoms with opposite charges attract each other.
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In an atom, electrons move around outside the nucleus.
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In some elements, electrons can also move from one atom to another.
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This movement of electrons produces electricity.
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Electricity, or electric energy, is a form of energy produced by moving electrons.
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Electricity can be changed to other forms of energy.
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People use electricity to run lights in homes, schools, and offices.
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Electricity also runs street lights and traffic lights.
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Lamps change electricity into light energy.
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Electricity changes to motion, or mechanical energy.
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Electric motors can be small enough to power a model train.
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They can be large enough to drive a huge freight train or a ship loaded with cargo.
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Electric motors even run some cars.
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Electricity can also change to heat energy.
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Toasters and electric ovens produce heat from electricity.
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So do hair dryers.
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Many homes are heated by electricity.
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What do a doorbell and a radio have in common?
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They both use electricity to produce sound energy.
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Radios use the electricity from batteries or outlets to produce sound.
Electricity:
MAIN IDEA AND DETAILS
What are four kinds of energy that electricity can be changed into?
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Electricity and Magnetism
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An electromagnet is a magnet made by coiling a wire around a piece of iron & running electricity through it.
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When electricity flows through a wire, the wire has a magnetic field around it.
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A single wire doesn’t have a strong magnetic field.
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Winding the wire into a coil makes the magnetic field stronger.
Each turn of the wire makes the field
stronger.
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Electromagnets:
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Electromagnet are useful because they can be turned on and off.
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In some buildings, they are used to hold heavy fire doors open.
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In an emergency, the electricity can be turned off.
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Because the magnet no longer works, the doors close, blocking the spread of a fire.
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Electromagnets are used on cranes in steel recycling centers.
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The magnets can lift heavy iron or steel objects, such as old cars.
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They can also be used to lift metal objects on and off ships.
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A much smaller electromagnet is used in a doorbell.
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When you press the button, electricity flows through the electromagnet, which pulls a steel spring toward it.
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The spring moves a clapper that hits the bell.
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A speaker in a stereo system is similar to a doorbell.
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An electromagnet makes parts inside the speaker vibrate.
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You hear the vibrations as sound.
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You have seen that electricity can produce magnetism.
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This also works the other way around—a magnet can produce electricity.
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That’s how an energy station works.
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In an energy station, a coil of wire turns inside the magnetic field of a huge magnet.
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When the wires cut across the magnetic field, electricity flows through the wires.
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Electricity travels from the station over a series of wires to schools, homes, and offices.
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Magnets produce the electricity we use every day.
Electricity and Magnetism MAIN IDEA AND DETAILS
What are some ways in which electromagnets are used?
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Electric Motors
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You know that electricity can be changed to mechanical energy.
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The motion of an electric device is produced by an electric motor.
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The electric motor is the opposite of a generator that produces electricity in an energy station.
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A motor contains a coil of wire that can spin inside the magnetic field of a permanent magnet.
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When the motor is switched on, electricity produces a magnetic field in the coil of wire.
2) The coil becomes an electromagnet.
3) The poles of this electromagnet are attracted and repelled by the poles of the permanent magnet.
4) This causes the electromagnet to spin.
5) The motion of the spinning coil can turn the blades of the blender or the fan.
Electric Motors MAIN IDEA AND DETAILS
What are the two main parts of a motor?
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