Understanding the nature of electrical current

Technology

Grade 8

Electricity

Module 12

The nature of electrical current

Electricity

In order to realize how essential electricity is to ones life, just turn off the electricity supply to your home for a while. It is difficult to realize that there are still people who get along without electricity, but usually even those people have battery-driven radios. Fortunately, most homes in South Africa have electricity. This commodity helps to improve people’s standard of living.

Activity 1

To demonstrate knowledge and understanding of the nature of electrical current, where it comes from, and the positive and negative impact thereof on the environment

ElectronProtonCoreNeutronElectron circuit

The atom is the building block of all material and it consists of the following parts: a core with protons and neutrons, and electrons that revolve in an orbit around the core. Electrons can be separated from the core and are then known as free electrons. When the free electrons move in the same direction, an electron flow (an electrical current) is formed.

There are two kinds of electrical currents, Alternating Current (AC) and Direct Current (DC). We mainly use alternating current in our homes for our stoves, refrigera­tors and lights. The electricity comes from a power-station, but many of the items in the home, for example torches, work with DC that comes from batteries. Many items such as cellular phones use AC to recharge their batteries that provide DC.

Assignment 1

1.1 How does electricity improve our standard of living / quality of life? (1 paragraph)

1.2 Provide the symbols for AC and DC. (Look at the back of your radio.)

1.3 How strong is the alternating current that is commonly used in South Africa?

1.4 Which company provides electricity in South Africa?

1.5 Name the different methods used by this company to generate electricity.

1.6 Choose one of the methods mentioned in 1.5 and describe the negative impact that the provision of this method of generation of electricity has on the environment.

1.7 Draw a diagram to represent the route that the power to your town/city/settlement follows from the power-station to your house.

Assessment

Memorandum

ACTIVITY 1

• The emphasis should be on the origin of electricity, namely the atom. Learners should also become thoroughly acquainted with the difference between AC and DC.

Assignment 1

1.1 Emits light and warmth. Can be used in electrical appliances, e.g. TV sets, computers, etc.

1.2 AC

1.3 220V

1.4 ESKOM

1.5 Nuclear power stations, hydroelectricity, coal-driven power stations, wind turbines.

1.6 Nuclear power: nuclear waste; radiationHydro power: disrupts ecologyCoal: smoke pollutionWind turbines: intrudes on the landscape

1.7 The emphasis should be on power lines, substations and transformers.