Electricity

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VOCABULARY

• Electricity                                   Fuse
• Circuit                                        Switch
• Insulator                                     Magnet
• Dynamo                                      Electro – magnet
• Device

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Electricity

Electricity is a form of energy produced by the flow of electrons.

          Sources of electricity.

-Cells i.e. Dry cell, Simple cell, chemical batteries, solar cell accumulators.
– Running water
-The sun.
-Fossil fuels.
-Wind.

ELECTRIC CELLS

Types of cells

1. Primary cells e.g.), Dry cells, a simple cell(wet cell)
2. Secondary cells/accumulators/storage cells. E.g. lead batteries, solar cells.

The dry cell.

Dry cell
A dry cell is an electric cell.
It stores chemical energy.
Structure of a dry cell

Functions of each parts of a dry cell
1.Bras cap: it acts as the positive terminal and contact.
2. Carbon rod: It is a non metallic conductor of electricity that acts as a positive pole.
3. Electrolyte: A liquid that conducts electricity.
4. Zinc can: a container in which the dry cell content is put and It acts as a negative terminal.  

5. Insulating top seal: It prevents the jelly from drying up.  
 N.B: I. A dry cell has voltage of 1.5 volts
The energy needed to push an electric current through a electric circuit is called voltage. Voltage is measured in volts.

A dry cell stores chemical energy which is later changed to electric energy.

Calculating voltage.
Exercise:

1. Juliet’s radio uses seven dry cells.

How many volts are needed if he is to use it to listen to news.

Solution:

1 dry cell= 1.5 volts

7 dry cells= ?

7dry cells X 1.5 Volts.

=10.5 volts

• How is the carbon rod useful in a dry cell?
• Suggest any one cause of dry cells losing their energy.
• What is the difference between electricity and electric energy/
• Identify any one source of electricity.

LESSON EIGHT

Simple cell (Wet cell):
It consists of a zinc plate and a copper plate dipping in dilute sulphuric acid.
The zinc plate acts as the negative pole.
The copper plate acts as the positive pole.
Sulphuric acid acts as the electrolyte.
The zinc and copper are called electrodes

An electrodes is a piece of metal that allows electric current to pass through it when placed in an electrolyte.

Simple cell (Wet cell):
It consists of a zinc plate and a copper plate dipping in dilute sulphuric acid.
The zinc plate acts as the negative pole.
The copper plate acts as the positive pole.
Sulphuric acid acts as the electrolyte.
The zinc and copper are called electrodes

An electrodes is a piece of metal that allows electric current to pass through it when placed in an electrolyte.

HOME MADE

                                                                        The bulb connected across the cell, begins to glow but after only a few minutes it becomes dimmer until it finally lights off.
Disadvantages of using a wet cell.

1. It is not very efficient. 

ii.It can only be used in an upright position.

1. It works for a short time

Questions.

1. What is the importance of the dilute sulphuric acid in a wet cell?
2. Why do wet cells lose their magnetism easily?
3.  State one disadvantage of using wet cells?
4. What acts as the electrolyte in a locally made wet cell?
5. Why does a wet cell light for a shorter time?