Energy to begin

Natural sciences grade 8

Energy: electricity, heat and light

Module 1: energy to begin

Energy is derived mainly from the sun and is available to us in various forms.

Some facts concerning energy:

• Energy is the capacity for doing work . We measure energy in joule (J).
• There are two main types of energy:
• The energy of action or motion is known as KINETIC energy
• The energy of position is known as POTENTIAL energy
• Energy also occurs in various forms, e.g.:

Chemical energy, which is obtained from chemical substances like petroleum, oil, gas, batteries and foodstuffs;

Electrical energy, which is derived from electricity;

Sound energy, from loudspeakers

Radiant energy, from light and heat. The sun is our largest source of radiant energy.

Nuclear energy , is stored in the nucleus of the atom.

Energy cannot be created or destroyed. It can only be converted from one form to another.

Activity:

To identify the different types of energy

[lo 2.1, lo 2.2, lo 2.4]

Assignment

In the following list, indicate the form of energy that is present:

1. Car battery
2. Paraffin stove
3. Wind-up toy car
4. Hair drier
5. Rubber band (shooting)
6. Radio
7. Food
8. A growing plant
9. Burning candle
10. Nuclear power station

Assessment of forms of Energy

Were you able to indicate the forms of energy correctly?

[LO 2.2]

Assessment

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

• recalls meaningful information;
• categorises information;

2.4 applies knowledge.

Memorandum

Assignment:

1. Car battery – CHEMICAL to ELECTRICAL

2. Paraffin stove - CHEMICAL TO HEAT

3. Wind-up toy car – POTENTIAL TO KINETIC

4. Hair dryer – ELECTRICAL TO HEAT

5. Elastic band (being shot) - POTENTIAL TO KINETIC

6. Radio – ELECTRICAL TO SOUND

7. Food – CHEMICAL TO KINETIC

8. A growing plant – RADIANT TO KINETIC

9. Burning candle – CHEMICAL TO LIGHT AND HEAT

10. Nuclear power station – KINETIC TO ELECTRICAL

• Explain this to grade 8 with the help of a simple example.
• It is generally known that the common light bulb provides us with light, but also becomes so hot that it can hardly be touched after a few moments. Approximately 100J of electric energy are converted to light energy AND heat energy within one second. The light energy has the value of about 5J, while the heat equals about 95J.
• The conversion therefore is as follows:

• ELECTRIC ENERGY TO LIGHT ENERGY AND HEAT ENERGY
• A light bulb therefore is altogether uneconomical!

• If you consider this, you will realise that the food provides the SOURCE OF ENERGY of human beings, but electricity and fuels provide all other aspects of energy. This brings us to the next learning unit.