Physics - Senior Secondary 2 - Electromagnetic Field

Electromagnetic Field

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TERM: 3RD TERM

WEEK: 10

Class: Senior Secondary School 2
Age: 16 years
Duration: 40 minutes for each of 5 periods
Date:
Subject: Physics
Topic: Electromagnetic Field
Subtopics:

  • The transformer
  • Power transmission
  • The induction coil

SPECIFIC OBJECTIVES:
By the end of the lesson, students should be able to:

  1. Understand the working principle of a transformer.
  2. Explain the concept of power transmission using transformers.
  3. Describe the function and operation of an induction coil.
  4. Investigate the effect of moving a magnet in a solenoid or a coil carrying current near a solenoid.

INSTRUCTIONAL TECHNIQUES:

  • Explanation
  • Demonstration
  • Questions and answers
  • Hands-on activity: Investigation of the effect of moving a magnet in a solenoid
  • Video clips on transformers, power transmission, and induction coils

INSTRUCTIONAL MATERIALS:

  • Solenoid
  • Magnet
  • Transformer (model)
  • Induction coil
  • Power source
  • Physics textbook
  • Whiteboard markers
  • Videos on transformers and induction coils

 

INSTRUCTIONAL PROCEDURES

PERIOD 1-5

PRESENTATION

STEP 1: INTRODUCTION

  • The teacher will ask students about their prior knowledge of electromagnetism and its applications, specifically in transformers and power transmission.
  • The teacher will introduce the topic of electromagnetic fields and how they are used in everyday technology.

STEP 2: EXPLANATION

  • The teacher explains the concept of a transformer and its function in changing voltage levels in an alternating current (AC) circuit.
    • Working Principle: A transformer operates on the principle of electromagnetic induction, where a primary coil induces a current in a secondary coil.
    • Types of Transformers: Step-up and Step-down transformers.
  • The teacher will explain power transmission and how transformers play a crucial role in the long-distance transmission of electricity by stepping up or stepping down voltage.
  • The teacher will describe the induction coil as a device that generates high-voltage electricity by repeatedly interrupting the current flow in a coil.

STEP 3: DEMONSTRATION

  • The teacher will demonstrate how to investigate the effect of moving a magnet in a solenoid. The teacher will move the magnet in and out of the solenoid and observe the induced current with the help of a galvanometer.
  • The teacher will demonstrate the function of a transformer by showing how the voltage can be increased or decreased by changing the number of turns in the primary and secondary coils.
  • The teacher will demonstrate the operation of an induction coil and explain its function in generating high-voltage electricity.

STEP 4: HANDS-ON ACTIVITY

  • Students will be divided into groups to investigate the effect of moving a magnet in a solenoid. Each group will use a solenoid, magnet, and galvanometer to observe the induced current.
  • Each group will also explore the function of a transformer and use it to demonstrate the change in voltage between the primary and secondary coils.

STEP 5: NOTE TAKING

  • The teacher will write a summary note on the board, which students will copy.

NOTE
Transformer:

  • A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction.
  • Step-up Transformer: Increases the voltage, decreases current.
  • Step-down Transformer: Decreases the voltage, increases current.
  • Formula for transformer operation:

V1/V2=N1/N2

Where:
V1 = Voltage in primary coil
V2 = Voltage in secondary coil
N1 = Number of turns in the primary coil
N2 = Number of turns in the secondary coil

Power Transmission:

  • Transformers are used in power transmission to increase the voltage for efficient long-distance transmission and to decrease the voltage for safe distribution to homes and businesses.

Induction Coil:

  • An induction coil is a type of transformer that produces high-voltage pulses by rapidly interrupting the current in a primary coil.
  • It is used in applications requiring high-voltage sparks, such as in spark plugs, radios, and other electronic devices.

EVALUATION

  1. What is the working principle of a transformer?
  2. What are the differences between a step-up and step-down transformer?
  3. Explain how power transmission works using transformers.
  4. What is the function of an induction coil?
  5. What is the relationship between the number of turns in the coils and the voltage in a transformer?

CLASSWORK:

  • Write down the principle of electromagnetic induction.
  • Draw and label a diagram of a transformer, indicating the primary and secondary coils.
  • List at least three uses of an induction coil.

 

CONCLUSION

  • The teacher will review the students' answers and provide feedback.
  • Students will reflect on the applications of transformers and induction coils in modern technology and power systems.

The teacher will emphasize the importance of transformers in ensuring efficient power transmission over long distances.