# Lesson Notes By Weeks and Term - Senior Secondary 1

Electric charges

Term: 2nd Term

Week: 4

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject:      Physics

Topic:-       Electric charges

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

1. Explain the meaning of electric charges
2. Discuss the way by which charges can be produced
3. Define conductors, insulators and electroscope
4. Discuss lightning and lightning conductor

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 reviews the previous lesson on gravitational field Students pay attention STEP 2 EXPLANATION He explains the meaning of electric charges and discusses how they can be produced Students pay attention and participates STEP 3 DEMONSTRATION He defines conductors, insulators and electroscopes and discusses lightning and lightning conductor 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

ELECTRIC CHARGES

These result as a flow of electrons from charged body to uncharged body.

TYPES OF CHARGES

1, Positive charge

2, Negative charge

PRODUCTION OF CHARGES

Electric charge can be produced by the following methods

i,By Friction: When uncharged polythene rod is rubbed with fur, electrons are transferred from the fur to the polythene during the rubbing.

The polythene then becomes negative charged. Also when an uncharged glass rod is rubbed with silk, electrons are transferred from the glass to the silk. The glass rod becomes positively charged.

ii,By Induction: This involves the production of an Electric charge by placing a charged body near an uncharged body .

The activity can be carried out in the following steps.

1. Bringing a positive Charge close to an insulated body
2. Earth the insulated body by momentarily touching it so that the positive charge conduct away
3. Remove inducing charge

iii,By Contact: This method involves bringing a charged object in contact with a neutral object. If a positively charged glass rod is brought near neutral insulated body, the body acquires the same charge as the glass rod.

CONDUCTORS

Conductors are materials that allow electron to pass through them easily, they can also conductor electricity. Examples are; some metals, graphite, acids, salt solution, the earth and human body.

INSULATORS

Insulators are material that do not allow electron to pass through them easily. Examples are; plastic, polythene, paper, ebonite, dry hair, silk, glass etc.

ELECTROSCOPE

An electroscope is an instrument used for detecting and testing small electric charges. It consist of a metal (brass) rod to which a thin gold-leaf (or aluminum leaf) is attached. The rod is by a brass cap or disc and insulated from the metal case.

A gold leaf electroscope can be charged by induction method. If a positive charged rod is brought near a positively charged electroscope, the leaf divergence increases more and decreases if it has opposite charge.

LIGHTNING: The atmosphere is known to contain ions or charged particles which have been produced by radiation from the sun body by what is known as cosmic radiation which enters the atmosphere from outer space.

Lightning is sudden discharge or neutralization of electric charges and it occurs when charges build up in a cloud

LIGHTNING CONDUCTOR

A lightning conductor is used to protect a building from lighting damage. It consists of a conductor made of a thick strip of metal cable to carry a large current without melting.

EVALUATION:   1. Define electric charge

1. State and explain the three ways electric charges can be produced
2. Write short notes on
3. conductors
4. insulators
5. electroscope
6. Explain lightning and lightning conductor

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively