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The Electromagnet

Lesson 67

3^rd Q

• Who among you have magnets of your own?
• That is a permanent magnet..
• Don’t you know that we can make a temporary magnet?
• Introduce the word “electromagnet”

• Name those appliances in the screen.
• These appliances used electromagnets to function

Activity 1

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Making My Own Electromagnet

Direction:

1. Get half meter long copper wire,2 dry cells,one big iron nail about 4 centimeters in length and a tape.
2. Wind the wire around the nail. Remove one centimeter of insulation from both ends of the wire.
3. Attach the ends to the poles of the battery.
4. Trace the path of electricity in the device you have just made.
5. Bring the iron nail near some needles. Observe how the iron nails behave. Predict what would happen if the wire was detached from the dry cell.
6. Detach one wire from one terminal of the dry cell.
1. What happen to the iron nail? Explain your observation.
2. What property is exhibited by the nail when electricity flows along its wire?

• Posting/reporting activity results by group.

1.What happens to the ends of the wire that are connected to the dry cell and you bring the iron nail near the needles?

2.What happens if you detach an end of the wire from one terminal of the dry cell?

3.What property is exhibited when electricity flows along the wire?

• An electromagnet is a temporary magnet that produces electricity when there is electric current through a coil of wire wrapped around an iron. It can only move nails or paper clips and tacks other materials made of steel, iron , cobalt,or nickel. To make the electromagnet work, there must be a complete circuit through which electrons can move. When a connection to a terminal is disconnected, the electromagnet losses its ability to magnetize.
• The strength of an electromagnet depends upon the number of turns it has on its coil, the materials used or the core and the amount of electricity in the wire.
• Electromagnets operate only when there is a flow of electricity in the col of wire. Its magnetism can be turned on and off at will.

• Electricity can be transformed into energy of motion or mechanical energy because of a discovery made by Hans Christian Oersted in 1820. He found out that a wire carrying electric current generates a magnetic field. This is called electromagnetism. This is made possible with the use of electromagnet which is made of metal rod as its core. Around this is coiled a piece of copper wire. The ends of the rod are connected to a source of electricity. When electric current flows on the wire , it produces a magnetic field and the rod produces magnetism. The it attracts objects made of metal.
• The strength of an electromagnet depends upon the number of turns it has on its coil, the materials used or the core and the amount of electricity in the wire.

• Why does the iron attract the needles when the ends of the wire coiled around it are connected to a dry cell?
• Why do the needles fail when both ends are detached?
• How does an electromagnet work? Describe its functions.

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• Huge and tiny machines use the electromagnet to produce mechanical/motion energy from electricity. Why are electromagnets preferred to other kind of magnets?

• Choose the letter that best complete the statement.
• An electric motor uses an electromagnet to change _____.

a. magnetic fields in the motor

b. magnetic poles in the motor

c. mechanical energy to electrical energy

d. electric energy to mechanical energy

2. An electric current in a wire coil produces _______.

a. another current b. a magnetic field

c. a generator d. a source of voltage

3. To strengthen an electromagnet, ______.

a. decrease the voltage b. increase the number of turns in a coil

c. put a non-magnetic substance in the coil

d. all of the above

• The following paragraph will describe correctly how the electromagnet works if the right words are selected to complete it. Write the correct word.

A piece of wire preferably copper is (1.coiled around, connected to) an iron rod. The iron rod serves as the (2.source of electricity, core).Then the ends of the wire are each connected to the (3.terminals,body)of a dry cell. The dry cell is the source of(4.electricity,magnetism).When the current flows through the wire it generates (5.electricity,magnetic field).This causes the metal rod or core to (6.attract,repel) things made of metal. This property is called (7.electromagnetism,electrometer).

Assignment:

• Bring again your materials on electromagnet for tomorrow’s activity.