# Lesson Planning of Electro-magnets

Lesson Planning of Electro-magnets

Subject General Science

Students` Learning Outcomes

• After studying this lesson, students will be able to:
1. Make an electromagnet with the help of a cell, an iron nail and wire, and show its working.
2. Explore different electromagnetic devices used in daily life.
3. Describe the relationship between electricity and magnetism in an electromagnetic device.

Science Process Skills

Observing, Classifying, Communicating, Inferring, Predicting and Experimenting

Information for Teachers

• A natural magnet is a mineral with magnetic properties (magnetite). An artificial magnet is a body of ferromagnetic material to which the property of magnetism has been communicated. … Temporary artificial magnets: those that produce a magnetic field only when an electric current circulates through them.

• The properties of the magnet that you have to consider are that its magnetic attraction exists even if the objects are in the water.

• The magnet has two poles, one north and one south, which are oppositely attracted. In this way the North Pole attracts the South Pole and the South Pole to the north.

• The energy that we have applied to the magnetic poles will make the magnet point in different directions, so the poles will deform.

• It is also possible to demagnetize a magnet by hitting the ends of it with a hammer, which will alter the order of the magnet.

Electromagnetic Devices:

• Is there any relation between electricity and magnetism? We have explored how electricity can change an iron nail into a magnet. In a dynamo a magnet is used to produce electricity. There are numerous devices in which this type of transformation is used. These are called electromagnetic devices. Electro motors and electric generators are well known examples of such devices.

Electric Motors:

• An electric motor converts electric energy into mechanical energy with the use of a magnet. When a current passes through a coil of wire placed in a magnetic field, the coil starts rotating. This is an electric motor. An electric fan, a grinding machine, a water pump are examples of electric motors

Electric Generator:

• An electric generator converts mechanical energy into electrical energy. So whenever a coil rotates inside a magnet field, current starts flowing through it. This is the electric generator.

Other Electromagnetic Devices:

• There are many other electromagnetic devices which we use in our daily life. Such as;

Ø  A telephone,

Ø  A microphone,

Ø  A loudspeaker,

Ø  A computer,

Ø  Fax machine and many more.

Material / Resources

Writing board, chalk / marker, duster, an iron nail, three cells, a switch, steel pins and connecting wires

Introduction

We can convert a piece of iron into a magnet with the help of a permanent magnet. Now we are using electric current.

Development

Activity 1

Methods:

• Divide the class into suitable groups and tell them to follow the given instruction:

1.      Take an iron nail at least 10 cm long.

2.      Wind an insulated copper wire very closely over it. This makes a coil.

3.      Connect the two ends of the coil to the battery of three cells through a switch.

4.      Without turning the switch on, bring some steel pins near one end of the nail. Does the nail attract them?

5.      Then turn the switch on and see if the nail attracts them now?

6.      Predict what will happen if the current is switched off?

7.      Now switch off the current and observe, what happens?

8.      Repeat the above procedure with a steel nail and find out the difference.

9.      What inference do you deduce from this activity?

Observation of the Activity:

1.      An iron nail or rod becomes a magnet when electric current passes through a coil around it. It is called an electromagnet.

2.      This type of magnet is a temporary magnet. It does n`t work permanently.

3.      If a steel nail is magnetized, it retains its magnetism even when current is switched off.

Sum up / Conclusion

• An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current, disappearing as soon as said current ceases. Whenever we have an electric current, a magnetic field will be present; this phenomenon is known as induction
• An electromagnet is a type of magnet that attracts metals with the help of electricity.
• Electromagnets are widely used in motors and generators, magnetic locks, loudspeakers, and the magnetic separation of materials, among many others. To better understand the concept of electromagnetism and how its entire mechanism works, we are going to create our own electromagnet!
• To create your own electromagnet you will need the following materials:

• Take the 3-inch nail and the thin coated copper wire and wrap the copper wire around the nail, leaving at least 10 inches at the end. Make sure you don’t overlap the wire when you wrap it around the nail. Take the scissors or utility knife and cut the nail, leaving 8-10 inches at the other end as well.
• The next step is to connect the wire to the ends of the stack. To do this, you must first strip the plastic covering of the copper wire and connect one end to the positive terminal of the dry cell and the other end to the negative terminal of the battery. Take your electrical tape and cover both ends of the wire to the battery terminals to keep them in place.
• Take available iron filings, clips, and other magnetic items to test your electromagnet.
• Electromagnets work as long as there is electricity running through a wire, as this will allow you to automatically generate a magnetic field. You must be wondering how electromagnets differ from the common magnets that go around in our house. Unlike common magnets, the magnetic field that the electromagnet creates is only temporary. The electromagnet will work as long as there is a continuous flow of electrons. On the other hand, common magnets do not need electrical current to work.
• Do you know what else you can do? Take a piece of paper and place the iron filings on it, keeping the electromagnet under the paper. See how the iron filings are arranged in the shape of the electromagnet’s magnetic field! Amazing, right?

Assessment
1. Which of the following is not an electromagnetic device?
i. Microphone
ii. Telephone
iii. Loudspeaker
iv. Magnetic compass

2. Which of the following is a temporary magnet?

a). Bar magnet

b). Magnetic compass

c). U shape magnet

d). Electromagnet

3. Fill in the blanks:

i. An electric motor converts _______ energy into mechanical energy.

ii. An electric generator converts ______energy into electrical energy.

iii. A speaker is ________ device

4. How can an iron nail be made electromagnetic by electric current?

5. Give some examples of electromagnetic devices. explain the working of any one of them.