SOME NATURAL PHENOMENA CLASS 8

 

SOME NATURAL PHENOMENA

 Some objects can be charged by rubbing with other objects.

 There are two kinds of charges — positive charge and negative charge

 Like charges repel and unlike charges attract each other.

 The electrical charges produced by rubbing are called static charges.

 When charges move, they constitute an electric current.

 An electroscope may be used to detect whether a body is charged or not.

 Attraction is not a sure test to know the presence of charge on a body.

 The process of transfer of charge from a charged object to the earth is called earthing.

 The process of electric discharge between clouds and the earth or between different clouds causes lightning.

 Lightning strike could destroy life and property.

 Lightning conductors can protect buildings from the effects of lightning.

 An earthquake is a sudden shaking or trembling of the earth.

 Earthquake is caused due to the disturbance deep inside the earth’s crust.

 It is not possible to predict the occurrence of an earthquake.

 Earthquakes tend to occur at the boundaries of earth’s plates. These boundaries are known as fault zones.

 Destructive energy of an earthquake is measured on the Richter scale. The

earthquake measuring 7 or more on Richter scale can cause severe damage to life and property.

 We should take necessary precautions to protect ourselves from earthquakes.