Short circuits 

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Short circuits

A short circuit is a path of low resistance towards flow of current through circuit.
Causes of short circuit

• Poor wiring when installing electricity in buildings.
• Pushing metallic objects in electric sockets.
• When bare electric wires get into contact.
• Wrong connection of wires in electric equipment.
• Overloading sockets.

Effects of short circuit.

• Destruction of electrical equipment.
• Fire that may burn the building.
• Lead to death of people and animals.

How to avoid short circuit

• Electric wires should be covered with an insulating material.
• Installation should be done by experts only.
• Repair of electric appliances should be done by experts.

STATIC ELECTRICITY

• It is the type of electricity where there is no flow of electrons.
• It is formed when two insulators are rubbed against each other.
• In nature static electricity can be seen when lightning occurs.
  

Lightning.

• This is static electricity in nature.
• When a positively charged cloud meets a negatively charged cloud, a huge spark is formed and may pass to the ground.
• During the passage of lightning, the surrounding air is heated strongly, expands suddenly and then contracts quickly as it cools.
• This air vibrates to produce the sound called thunder.
  Advantage of lightning.
• Lightning fixes nitrogen into the soil.

Preventing effects caused by lightning.

• Avoid sitting under tall trees when it is raining.
• Install lightning conductors on buildings.

How lightning conductors reduce risks to the building.

• They provide route for electrons to pass into the ground without damaging the building.
  Differences between static electricity and current electricity

	Static	Current
1	Takes place in insulators.	Takes place in conductors.
2	The charge is on the surface.	Charge is inside the conductor.
3	The charge does not flow.	Charge flows through the conductor from one place to another.
4	Protons (+) and electrons (-) are both necessary for this type of electricity.	Only electrons flow.

 Importance of electricity.(lesson ten), week two.

•  Cooking
•  Lighting
•  Run machines like radios,

Advantages of electricity in solving everyday problems.

• It is quick.
• It is clean.
• Easy to use.
• Conserves the environment.
  
  Disadvantages of electricity.
• It is expensive to install.
• Electricity can shock.
• It can burn buildings.

Safety precautions in handling electricity and electrical appliances.

• Never touch a switch with wet hands
• Avoid over loading the socket.
• Avoid repairing the appliance when not trained.
• Avoid pushing metallic objects into sockets.
• Never open anything that uses electricity if not an expert.
• Never touch an electric wire that has fallen from an electric pole.
• Never take shelter under tall trees during thunderstorm.

Topical questions

1. Briefly explain the term electricity.
2. Why electricity is called a form of energy?
3. Give any one way in which electricity can prevent deforestation.
4. Why is it important to properly handle electric appliances?
5. Draw a symbol of an electric bulb.
6. Suggest any one way in which we can prevent our electric appliances from being destroyed by electricity.
7. State any one difference between conductors and insulators.
8. Why are electric wires carrying current from the source raised some meters high from the ground?
9. Cite any one disadvantage of using electricity in the environment
10.  Draw a diagram to show the flow of current.
11. Cite any one danger of lightning to the environment.
12. State the static electricity in nature.
13. Briefly explain how to overcome the dangers of caused by short circuits in the environment.
14. Why is the filament of an electric bulb coiled?
15. How is a fuse important in an electric circuit?