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Physics for Kids
Electromagnetism and Electric Motors
The word "electromagnetism" in physics is used to describe one of the fundamental forces of nature. This force is between subatomic particles such as protons and electrons. It helps to hold matter together.
Electromagnetism is also used to describe how a magnetic field is created by the flowing of electric current. We will be discussing this type of electromagnetism on this page.
When an electronic current flows through a wire, it generates a magnetic field. This is an important concept in electricity. The magnetic field can be increased by coiling the wire. This allows more current to flow through a smaller distance and increases the magnetic field.
When current is flowing through a wire, the magnetic field rotates around the wire. The direction of the current determines the direction of the magnetic field. You can figure out the direction of the magnetic field using the "right-hand rule".
To determine the direction of the magnetic field, look at the picture above. Take your right hand and point your thumb in the direction of the current (I). Now wrap your fingers around the wire. Your fingers will point in the direction of the rotation of the magnetic field (B).
One of the important applications of electromagnetism is the electric motor. An electric motor converts electrical energy into physical movement. Electric motors generate magnetic fields with electric current through a coil. The magnetic field then causes a force with a magnet that causes movement or spinning that runs the motor.
Electric motors are used in all sorts of applications. There are even several electric motors inside your computer including one to turn the fan, one to open and shut the CDROM drive, and one to operate the hard drive.
Another important application of electromagnetism is induction. Induction is when movement is used to create electricity (the opposite of using electricity to create movement). As a wire is moved through a magnetic field, current will begin to flow through it.
Electric generators convert mechanical energy into electrical energy using induction. As a coil of wire is spun between two opposite magnets, an electric current is generated that can be used to power electronic devices.
Generators can get their power from a wide variety of sources. Two popular electric generators of renewable energy include hydropower and wind power.
Fun Facts about Electromagnetism and Electric Motors
- Some electric generators can be driven by human power such as a hand crank or a bicycle to generate electricity.
- Danish physicist Hans Orsted was the first to discover that a magnetic field was produced by the flow of electric current.
- American physicist Joseph Henry discovered electromagnetic inductance and built the first electromagnetic motor.
- Loudspeakers use electromagnets to vibrate the cone and produce sound.
- Using electromagnetism, powerful magnets can be turned on and off using electricity, unlike permanent magnets.
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