Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: Basic Electronics
Curriculum Theme: Basic Electronics
Previous Lesson: Electro-Magnetism: Key Terms and Inductance.
Topic: Application of electro-magnetism (e.g., electric bell, relay, transformer). Construction of any of the following (electric bells, relays, and transformers).
Subject Matter: application of electromagnetism in electric bell, application of electromagnetism in relay, application of electromagnetism in transformer, basic steps in constructing a simple electric bell, basic steps in constructing a relay or transformer

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define electromagnetism.
Identify various applications of electromagnetism.
List the basic steps involved in constructing a simple electric bell, relay, or transformer.

Affective Domain:

Appreciate the importance of electromagnetism in daily life.
Show interest in practical construction of electronic devices.

Psychomotor Domain:

Construct a simple electric bell, relay, or transformer based on given steps.

Work cooperatively with peers during practical activities.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (JSS 1-3)
State Unified Scheme of Work for Basic Electronics SSS 1
Basic Electronics for Senior Secondary Schools by A.O. Okoro
https://www.google.com/search?q=electromagnetism+applications
https://www.youtube.com/watch?v=electromagnetism_bell_relay_transformer

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts illustrating applications of electromagnetism (electric bell, relay, transformer).
Insulated copper wire, soft iron core, battery, switch.
A small bell gong, connecting wires, tools (e.g., pliers, wire strippers).
A pre-constructed simple electric bell, relay, or transformer for demonstration.

Rationale for the Lesson

This lesson helps pupils understand how electromagnetism is used in common devices around them. It enables them to connect theoretical knowledge to practical applications, which is important for developing their technical skills and problem-solving abilities.

Prerequisite/Previous Knowledge

Pupils are expected to have prior knowledge of basic electricity, magnetic fields, and conductors.

Lesson Content/Board Summary

Application of Electromagnetism and Construction of Devices

What is Electromagnetism?

Electromagnetism is the interaction of electric currents and magnetic fields. An electromagnet is a temporary magnet created when electric current flows through a coil of wire wound around a soft iron core.

Application of Electromagnetism in Electric Bell

An electric bell uses an electromagnet to produce sound. When current flows, the electromagnet attracts an armature, which causes a hammer to strike a gong. Breaking the circuit causes the electromagnet to release the armature, which then returns to its original position by a spring, completing the circuit again to repeat the process.

Application of Electromagnetism in Relay

A relay is an electrically operated switch. It uses an electromagnet to open or close a circuit. When current flows through the coil of the electromagnet, it attracts an armature, causing a set of contacts to change position, thereby switching another circuit on or off.

Application of Electromagnetism in Transformer

A transformer uses the principle of electromagnetic induction to change AC voltage levels. It consists of two coils (primary and secondary) wound around a common soft iron core. When an alternating current flows through the primary coil, it creates a continuously changing magnetic field in the core, which induces an alternating voltage in the secondary coil.

Basic Steps in Constructing a Simple Electric Bell

The following are the basic steps to construct a simple electric bell:

Obtain a soft iron core (e.g., a large iron nail).
Wind insulated copper wire tightly around the iron core to form a coil.
Mount the electromagnet, an armature with a hammer, and a bell gong on a wooden base.
Connect the coil, a battery, a switch, and the contact points for the armature in a series circuit.
Adjust the armature so that the hammer strikes the gong when the electromagnet is activated.

Basic Steps in Constructing a Simple Relay or Transformer

The following are the general steps to construct a simple relay or transformer:

Obtain a suitable soft iron core (e.g., U-shaped for relay, laminated for transformer).
Wind insulated copper wire to form the primary coil (and secondary coil for a transformer).
For a relay, position an armature and contact points near the electromagnet.
For a transformer, ensure the primary and secondary coils are magnetically linked by the core.
Connect the coils to a power source and test the functionality (switching action for relay, voltage transformation for transformer).

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and reviews the previous lesson on basic magnetism. The teacher then asks pupils to mention any device that uses magnetism to work, guiding them towards understanding electromagnetism.
Pupils’ Activity: Pupils respond to greetings and attempt to answer the questions, recalling previous knowledge.
Learning Point: Pupils recall prior knowledge of magnetism and are introduced to the concept of electromagnetism applications.

Step 2: Explanation of Electromagnetism and its Applications

Time: 10 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher defines electromagnetism and explains how an electromagnet works. Using charts, the teacher introduces various applications of electromagnetism, such as electric bells, relays, and transformers, giving a brief overview of each.
Pupils’ Activity: Pupils listen attentively, observe the charts, and ask questions for clarification.
Learning Point: Pupils understand the definition of electromagnetism and identify its key applications.

Step 3: Application of Electromagnetism in Electric Bell

Time: 7 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher focuses on the electric bell. Using a diagram or a pre-constructed model, the teacher explains in detail how an electric bell operates based on the principle of electromagnetism. The teacher demonstrates the working mechanism.
Pupils’ Activity: Pupils observe the demonstration, follow the explanation, and ask relevant questions.
Learning Point: Pupils understand the working principle of an electric bell.

Step 4: Application of Electromagnetism in Relay and Transformer

Time: 8 minutes
Teaching Skill: Explanation/Comparison
Teacher’s Activity: The teacher explains the application of electromagnetism in relays, describing their function as electrically operated switches. The teacher then explains how transformers use electromagnetic induction to change voltage levels, highlighting their importance in power distribution.
Pupils’ Activity: Pupils listen and take notes, understanding the functions of relays and transformers.
Learning Point: Pupils learn about the applications of electromagnetism in relays and transformers.

Step 5: Demonstration of Construction Steps

Time: 10 minutes
Teaching Skill: Demonstration/Practical
Teacher’s Activity: The teacher demonstrates the basic steps in constructing a simple electric bell, relay, or transformer using the available instructional materials. The teacher guides pupils on how to wind coils, connect components, and test the device.
Pupils’ Activity: Pupils observe the demonstration carefully, noting the materials and procedures involved in construction.
Learning Point: Pupils observe the practical steps for constructing electromagnetic devices.

Step 6: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define electromagnetism.
Mention two applications of electromagnetism.
Explain how an electric bell works.
List three basic steps in constructing a simple electric bell.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 7: Conclusion

Time: 5 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key learning points of the lesson, reiterating the definition of electromagnetism and its various applications, as well as the basic construction principles. The teacher then assigns homework related to the topic.
Pupils’ Activity: Pupils listen to the summary, ask any final questions, and copy down the homework.
Learning Point: Pupils consolidate their understanding of the lesson.

Lesson Keywords

Electromagnetism – The interaction of electric currents and magnetic fields.
Electric Bell – A device that uses an electromagnet to produce sound.
Relay – An electrically operated switch that uses an electromagnet.
Transformer – A device that changes AC voltage levels using electromagnetic induction.
Soft Iron Core – A material easily magnetized and demagnetized, used in electromagnets.
Armature – The moving part in an electric bell or relay that is attracted by the electromagnet.

Differentiation

For pupils who grasp concepts quickly, the teacher may provide more complex circuit diagrams or challenge them to explain the differences between step-up and step-down transformers. For pupils needing more support, the teacher will provide simplified diagrams, extra verbal explanations, and one-on-one guidance during the practical demonstration.

Note for teachers using this lesson plan

Ensure all safety precautions are taken during practical demonstrations and construction activities, especially when dealing with electrical circuits. Supervise pupils closely during any hands-on work. Encourage pupils to experiment and explore the concepts further at home with safe materials.