Electromagnetic Field SS3 Physics Lesson Note

SPECIFIC OBJECTIVES: At the end of the lesson the students should be able to;

1. State the application of electromagnet
2. List the use of electromagnetic fields in home appliance
3. Explain the concept of electromagnetic field

INSTRUCTIONAL RESOURCES: 

1. A  chart  showing electromagnets

LESSON PRESENTATION

Step 1: Identification of prior ideas:

Mode: the entire class

Teacher’s Roles: Ask the students the following question: What are electromagnets?

Students Roles: Respond to the teacher’s question 

Step 2: Experimentation / Exploration:

Mode: the entire class

Teacher’s Role:  The teacher uses the chart to explain the electromagnetic field  

Students’ Roles: The students listen and observe the activities.

Step 3: Discussion:

Mode: Whole

Teacher’s Role: Using the following question below, the teacher guides the students in discussing the activities

1. What are electromagnets?
2. State two home appliances that use an electromagnetic field
3. List three uses of electromagnets.

Student Roles: The students answer the question, by contributing their ideas to the discussion. The teacher then summarises the lesson topic as follows:   

 APPLICATION OF ELECTROMAGNETIC FIELD

An electromagnet is a kind of magnet where the magnetic field is created by an electric current. The uses of electromagnets are given here to help learners understand the topic more effectively. Electromagnets can be considered temporary magnets that function with the help of an electric current. The magnetic strength of an electromagnet can be easily altered by varying the amount of electric current and its polarity can be changed by varying the direction of electric current. 

Electromagnets are used for various purposes and a day-to-day basis, for example, electromagnets are used in large cranes in numerous electromechanical and electronic devices. Some common uses are given below. 

Uses of electromagnets. 

1. Generators Motors and Transformers
2. Electric buzzers and bells 
3. Headphones and loudspeakers 
4. Relays and Valves. 
5. Data storage devices like VCRs, tape recordings, hard discs etc.
6. Induction cooker 
7. Magnetic locks
8. MRI Machines
9. Particle accelerators 
10. Mass Spectrometers.

Uses in home appliances.

Most of the electrical appliances in the home use electromagnetism as the basic working principle. Some electromagnet uses in the home include an electric fan, electric doorbell, induction cooker, magnetic locks, etc. In an electric fan, the electromagnet i.e. induction keeps the motor rotating on and on making the blade of the fan rotate. Also in an electric doorbell, when the button is pressed, due to the electromagnetic forces the coil gets energised and the doorbell sounds. 

  APPLICATION: The teacher guides the students to mention the application of electromagnets as follows;

1. Headphones
2. Loudspeaker
3. Motors 
4. Generator

ASSIGNMENT:    Study medical uses of the Electromagnetic field for the next class.                              

REFERENCE MATERIAL:

1. New system Physics for Secondary School by Dr Charles Chew et al.
2. New School Physics by MW Anyakoha
3. Internet facility