1. this is electricity produced by burning Fuels like petrol, Diesel are used to run or turn generators. These produce electricity.

2.       Chemical energy in fuel plus mechanical energy from generators change to electric energy.

3.       Thermal electricity is more expensive to produce.


  1. This is electricity produces by using energy from the sun.
  2. The Solar cells (panels) are used to trap the energy from the sun to produce electricity.
  3. This electricity is stored in batteries.
  4. Solar electricity is usually in form of Direct Current (D.C).


  1. It is produced by using heat energy from underground.
  2. This type of electricity is mainly produced in areas where there are volcanic actions (Rift valleys).
  3. In this type of electricity pipes are sunk down where there is heat from under ground. Water is pumped there.
  4. It is heated by the underground heat and pushed back as steam under high pressure.
  5. The steam helps to turn turbines. The turbines turn generators that produce electricity.
  6. This type of electricity is called Geothermal Electricity.


  1. In plains or flat areas there is constant blowing of wind with less disturbance. Wind mills can be constructed in such areas.
  2. The wind turns the flaps of the windmills which in turn rotate the generator to produce electricity.
  3. Electricity from using wind is termed as Mechanical Electricity.


  1. Some minerals like uranium have the ability to break up and produce energy.
  2. This energy can be used to produce electricity.
  3. The splitting atoms produce a lot of heat used to boil water to produce steam that turns turbines.

4.       Electricity got from energy got from breaking up nuclear of some metals is called Nuclear Electricity.


  1. This is obtained by using machines to turn dynamos to produce electricity.
  2. Bicycles and motorcars have dynamos that produce electricity that they use. Some of this electricity is stored in Batteries.


This is electricity obtained from chemicals. These chemicals can be found in dry cells and batteries.


  1. Dry cells.
    1. Wet cells
    1. Solar batteries.
    1. Generators
    1. Batteries.




An electric circuit is complete path taken by the flow of current. A simple electric circuit is made up of:-

  • The source of electricity (Dry cells); to produce electricity.
  • The conductor; to transmit current.
  • An appliance (bulb); to show whether the circuit is complete.
  • A switch; to break or complete the circuit.

Symbols of parts of an electric circuit

circuit parts

          THE DRY CELLS

  1. The dry cells supply electricity in a simple circuit.
    1. Chemical energy stored in the cells is changed to electric energy.
    1. A dry cell is manufactured with 1.5 volts of electricity.
    1. If the dry cells are arranged wrongly, the cancel each other and the bulb will not give light.
dry cells


  1. In a simple circuit, the bulb is the electric appliance.
  2. The work of an electric appliance is to change electric energy to required form of energy.
  3. In this case, the bulb changes electric energy to heat and light energy.
bulb parts

Functions of some parts of a bulb.

Glass envelope

It holds nitrogen and inert gases.

Examples of inert gases used in the bulb

  1. Neon
    1. Helium
    1. krypton and
    1. Argon gases.

Note:     These inert gases are used to prevent the filament from burning.

The filament

  1. The filament is a thin coiled wire enclosed in a glass envelope.
  2. It is coiled to increase resistance against electricity.
  3. Tungsten or wolfram is the most commonly used conductor when making fillaments of  electric bulbs.
  4.  Tungsten or wolfram is used because ;

i) it has a high melting point( does not melt easily).

ii) It has a very high resistance on electricity.

  • The energy change that occurs in the filament is; electric energy is changed to heat and light energy.

Examples of electric appliances

  1. Radios.
    1. Bulbs
    1. Televisions.
    1. Fridges.
    1. Flat irons
    1. Funs.
    1. Cookers.

Energy changes in some electric appliances.

  1. A bulb changes electric energy to heat and light energy.
  2. A cooker changes electric to heat energy.
  3. A radio changes electric energy to sound energy.
  4. A television changes electric energy to light and sound energy.

Why a bulb may not give light in a circuit.

  1. The dry cell/battery may be used up.
  2. The dry cells may be poorly arranged.
  3. The bulb may have blown.
  4. The conductor may be broken.
  5. The circuit may be incomplete.


  1. Things that allow electricity to pass through them are called conductors.
  2. Conductors commonly used in transmitting electric current are wires made from copper and aluminium.
  3. All metals are conductors of electricity.

i) Copper

ii) Iron

iii) Aluminium

iv) Silver

vi) Tin

vii) Gold.

  • Of the metals silver is the best conductor of electricity. It is not commonly used to make wires because it is very expensive.
  • Carbon is the only solid non-metal that conducts electricity.
  • Some liquids conduct electricity. Liquids that conduct electricity are known as electrolytes.

Examples of electrolytes.

  1. Urine.
  2. Un distilled water.
  3. Salt water solution.
  4. Acid.


  1. These are substances/materials that do not allow electricity to pass through them.
  2. Insulators are also called non conductors.

Examples of in Insulators.

  1. Wood
    1. Plastic
    1. Dry cloth
    1. Air
    1. Pure water
    1. Paper
    1. Rubber and
    1. glass

Uses of Insulators:

  1. Insulators are used to cover conductors so that electricity is transmitted safely.(insulation of conductors)
  2. The most common insulators used are Rubber and Plastic.
  3. Used to make protective gears like gloves that are used by people who handle electric materials.