Lesson Notes By Weeks and Term - Junior Secondary 1

Basic electricity 2

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TERM – 3RD TERM

WEEK EIGHT

Class: Junior Secondary School 1

Age: 12 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC TECHNOLOGY

Topic: BASIC ELECTRICITY 2

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Define and identify measuring Instruments
  2. Define and describe the working principle of a transformer.
  3. Describe a Stabilizer
  4. Identify appliances and Accessories that utilize electricity.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures/diagram of a transformer

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher introduce and identify measuring instruments used in electricity.

Students pay

attention

STEP 2

EXPLANATION

Teacher describe and discusses the working principle of a transformer

Students pay

attention and

participate

 

STEP 3

DEMONSTRATION

Teacher discusses the uses of stabilizer.

Teacher identify appliances that utilizes electricity.

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

 

The students

copy the note in

their books

 

NOTE

BASIC ELECTRICITY 2

Basic electricity measuring instruments are tools used to quantify and assess electrical parameters in a circuit. Basic electricity measuring instruments include:

  1. Multimeter: Measures voltage, current, and resistance. It's versatile and essential for basic electrical troubleshooting.
  2. Voltmeter: specifically measures voltage in a circuit.
  3. Ammeter: Measures electrical current in a circuit.
  4. Ohmmeter: Measures electrical resistance in a circuit.
  5. Wattmeter: Measures electrical power consumption.
  6. Galvanometer: Detects and measures small electric currents.

Transformer

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It consists of two coils, typically wound around a common iron core. The primary coil is connected to the input voltage source, and the secondary coil is connected to the output. When an alternating current (AC) flows through the primary coil, it produces a changing magnetic field that induces a voltage in the secondary coil.

Types of transformers

  1. A step-up transformer is a type of transformer that increases the voltage from the primary winding to the secondary winding. In other words, the output voltage is higher than the input voltage. Step-up transformers are commonly used in power transmission to increase voltage for efficient long-distance electricity transfer, minimizing power losses.
  2. Step-down transformer is a type of transformer that decreases the voltage from the primary winding to the secondary winding. Here, the output voltage is lower than the input voltage. Step-down transformers are often employed in power distribution networks to reduce voltage levels for safer and more practical use in homes, businesses, and various electrical devices.

Working principle of a transformer

The working principle of a transformer is based on electromagnetic induction. It consists of two coils, a primary coil, and a secondary coil, usually wound around a common iron core. When an alternating current (AC) flows through the primary coil, it produces a changing magnetic field around the coil. This changing magnetic field induces a voltage in the secondary coil according to Faraday's law of electromagnetic induction.

The induced voltage in the secondary coil is directly proportional to the turns ratio of the two coils. If the secondary coil has more turns than the primary, the transformer is a step-up transformer, increasing the voltage. Conversely, if the secondary coil has fewer turns, it's a step-down transformer, decreasing the voltage.

Stabilizer

A stabilizer is a device designed to regulate and maintain a constant output voltage. It is particularly useful in situations where the input voltage may vary, helping to protect electronic devices from voltage fluctuations.

There are different types of stabilizers, but the most common is the voltage stabilizer. It ensures a steady voltage supply to connected devices by adjusting or stabilizing the incoming voltage.

Electrical appliances and accessories

Electrical appliances are devices powered by electricity for various household or industrial purposes. Examples include refrigerators, washing machines, television, speakers, IOT, microwaves etc. Accessories are additional items that complement or enhance these devices, like power cords, adapters, or extension cords.

EVALUATION: 1. What are measuring instruments? Identify 5 measuring instruments for electrical work.

  1. What is a transformer?
  2. Describe the working principle of a transformer
  3. Identify and discuss the types of transformer you know.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively