6.1 Generation of Electricity

• Energy sources can be classified into two main groups,

1. Renewable energy sources - Energy sources that can be replaced continually and will never deplete.

2. Non-renewable energy sources- Energy sources that can be replaced continually and will never deplete.

• Examples

1. Hydro energy, Wave energy, Solar energy, Tidal energy, Wind energy, Biomass energy & Geothermal energy (Renewable energy sources).

2. Nuclear energy, Coal, Natural gas & Petroleum (Non-renewable energy sources)

• There are various types of electricity generator, such as thermal generator, hydroelectric generator, biomass generator, nuclear generator and solar energy generator.

• Generally, all these electrical energy generators use the same principle of generation. The turbine turns the dynamo that is connected to it. The dynamo has a wire coil placed in between a magnet. The wire coil cuts across the magnetic lines of force and electric current is produced.

Electric current is divided into two types:

1. direct current (d.c.)

2. alternating current (a.c.)

DIRECT CURRENT (D.C)

• Direct current is an electric current that flows in one direction only.

• Examples of devices that use direct current are torchlight, toys and calculators.

• Sources of direct current are Solar cell, accumulator and batteries.

ALTERNATING CURRENT (A.C)

• Alternating current is an electric current that flows in constantly reversing directions.

• Examples of devices that use alternating current are rice cooker, air conditioner and hair dryer