Electricity - Class 7 Science Revision Notes

• Sources of Electricity.
• Good and Bad Conductors of Electricity
  • Electrical Appliances
  • Safety when Dealing with Electricity
• Lightning and Safety Measures.
  • Precautions against Lighting during Thunderstorm.

This is a form of energy.

Sources of Electricity.

There are two forms of electricity. ie Static and current electricity.

Static electricity is produced by rubbing two surfaces against each other.

Current electricity is produced from:

• Hydroelectric dams
• Diesel generators Car batteries.
• Geothermal wells.
• Torch cells.
• Solar batteries

Good and Bad Conductors of Electricity

Good Conductors - These are materials that allow electricity to pass through them.

Bad conductors -These are materials that do not allow electricity to pass through them.

Electrical Appliances

•  An electric iron-used for pressing clothes.
• An electric cooker- used for cooking.
• An electric kettle-Used for boiling water or making tea.
• Radio-Used to receive information transmitted from stations.

Safety when Dealing with Electricity

• Don't work near mains.
• Don't have cables running under a carpet.
• Don't overload sockets by plugging in many electrical appliances.
• Never throw objects at a wire carrying electricity.
• Don't touch sockets and swiches with wet hands.
• Don't try to repair electrical appliances unless you have the knowledge of what you are doing.

Lightning and Safety Measures.

Lightning is a strong form of static electricity that is caused by the charges brought about by clouds .

Lightning arrestors are always fitted on tall buildings so that it when lighting strikes,the charges reach the ground

Precautions against Lighting during Thunderstorm.

• Use shoes with rubber soles while walking in the open on a rainy day.
• Don't stand on a pool of water when its raining.
• Avoiding leaning against the wall when its raining.
• Avoid carrying metallic and sharp-pointed objects when it is raining.
• When lightning strikes,it often hits tall objects before spreading to other objects in the area.
• Avoiding walking in open fields.