Basic Electricity - Senior Secondary 2 - Direct current generation

Direct current generation

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TERM: 1ST TERM

WEEK SEVEN

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: DIRECT CURRENT GENERATION

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

I.)  Define a DC generator

II.) Identify the principles of operation of DC generators

III.) Identify the constructional features of DC generators

IV.) State the uses of DC generators

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher explains the meaning of DC generator and discuss the principles of operation of DC generators

Students listens attentively to the teacher                                                                          

STEP 2

EXPLANATION

Teacher Identify and discuss the constructional features of a generator.

Teacher discusses the uses of DC generators.

Students exhibit attentiveness and active engagement

STEP 3

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

 

NOTE

DIRECT CURRENT GENERATION

A DC generator field system is a system used to produce a magnetic field in the armature of a DC generator, enabling the generation of electricity through the process of electromagnetic induction.

Principles of operation of a DC generator

  1. Faraday's Law of Electromagnetic Induction: When a conductor (armature) moves within a magnetic field, an electromotive force (EMF) is induced in the conductor, generating electricity.
  2. Fleming's Right Hand Rule: When the thumb, forefinger, and middle finger of the right hand are positioned perpendicular to each other, with the thumb indicating the direction of motion, the forefinger representing the direction of the magnetic field, and the middle finger pointing in the direction of the induced current, the rule determines the direction of the induced current.

Constructional features of DC generators

  1. Armature: The rotating part of the generator where the induced EMF is produced.
  2. Field Windings: Coils of wire wound around the pole pieces to create the magnetic field.
  3. Commutator: A segmented metal ring connected to the armature, used to convert alternating current to direct current.
  4. Brushes: Carbon or graphite contacts that maintain electrical contact with the commutator, transferring current between the armature and external circuit.
  5. Pole Pieces: Pieces of ferromagnetic material that concentrate the magnetic field within the armature.

Uses of DC generators

  1. Backup power supply in remote locations or during emergencies.
  2. Powering small electrical devices or appliances.
  3. Providing power in mobile applications such as vehicles or boats.
  4. Used in renewable energy systems like wind turbines and hydroelectric plants.
  5. Providing electricity in areas where AC power is unavailable or impractical.

EVALUATION: 1.  What is a DC generator?

  1. Discuss briefly principles of operation of a DC generator
  2. Identify 5 constructional features of a DC generator
  3. State 4 uses of DC generators

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively