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Electromagnets and Experiment
by Jeanette Cain
An electromagnet is a device made of a core and a coil of wire used to convert electric energy into work. The core needs to be able to give a
magnetic flow, but it also needs to lose the electric flow when the coil becomes de-energized. The electric power to the electromagnet coil is changed to a useful magnetic flow in the core of the
coil.
Electromagnets are useful when magnetism is not needed all the time. Three types of electromagnets:
1. lifting or carrying with a high force that operates through a short stroke; specifically for the purpose of holding; direct current electromagnets have designs similar to permanent magnets,
which will require recording any leakage factors. It must also be able to get rid of the heat which is created by electrical losses, without going above an excessive temperature.
2. clapper or armature type with a medium force and stroke; based on the horseshoe shaped core that has coils on one end or on both legs and a flat armature centered to come close to these legs;
and,
3. plunger (solenoid) type, which has a wide range of force and stroke relationships within an iron core or shell-movable parts pass through and operate within the coil's core. This type magnet
is used in industrial machinery-contractors and mechanical operators.
Each one has specific applications. Electromagnets have many uses in industry, homes and scientific research. Unlike permanent magnets, electromagnets can be turned on and off and make stronger
magnetic fields. Households use electromagnets as electric door bells and electric motors in appliances. Industries use larger electric motors with electromagnets. The magnetic vibrator uses
electromagnets to make rapid vibrations that cannot be heard. These magnetic vibrators are used to push pipes into the ground, to wash dirt from delicate mechanisms, and to cut hard
substances.
Electromagnet Experiment Set-up:
You will need:and adult, or friend, a flat iron bar shaped like a "U", insulated wire, two dry cell batteries, and a compass.
Making an electromagnet: wrap two layers of the insulated wire around the "U" shaped flat iron bar. Strip about an inch from each end on the wire.
Using the Experiment:
First connect the wire to the two batteries. Hold the compass with your first three fingers, and then pass the compass between the electromagnets two poles. Does the needle point to the poles?
When the current is turned on your electromagnet will pick up iron objects. Does your electromagnet pick up iron objects?
You may want to experiment "mapping" the magnetic field of your electromagnet. Other ways to change your experiment is to change the number of wire turns and the number (using more than 2) of
batteries, which will increase the magnet's ability to lift. The more batteries and the more wire turns you use will increase the strength of your magnet.
Editors. The World Book Encyclopedia. World Book-Childcraft International, Inc: Chicago. 1990
Further Study:
Electromagnetism - A-to-Z Science
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