Current Affairs 8th Class

Category : 8th Class

Some Natural Phenomenon

·                     Lightning is a huge electric spark. A lightning strike could destroy life and property.

·                     Benjamin Franklin, in 1752, showed that lightning is associated with electricity.

·                     Objects can be charged by rubbing with other objects.

·                     The electrical charges generated by rubbing are static. They do not move by themselves. When charges move, they constitute an electric current.

·                     There are two kinds of charges - positive charge and negative charge.

·                     When a glass rod is rubbed with silk, it is said to acquire positive charge. In the same way, when a glass rod is rubbed with wool, it is said to acquire negative charge.

·                     Like charges repel and unlike charges attract each other.

·                     An electroscope is an early scientific instrument that is used to detect the presence and magnitude of electric charge on a body.

·                     The process of transfer of charge from a charged body to the earth is called earthing,

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

·                     Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current.

·                     Lightning conductors installed at the top of the buildings protect them from lightning by allowing the discharge to go through them to the earth.

·                     A sudden shaking or trembling of the earth is called an earthquake. It is caused by disturbances occur deep inside the earth's crust.

·                     Despite of the advancement of scientific technologies, it is not possible to predict the occurrence of an earthquake.

·                     Earthquakes generally tend to occur at the boundaries of earth's plates. These boundaries are called as fault zones.

·                     A seismograph is the device that scientists use to measure earthquakes.

·                     The power of an earthquake is expressed in terms of magnitude on a scale called Richter scale. It is a logarithmic scale.

·                     The earthquake measuring 0-2 is considered as mild while an earthquake having intensity 7 or more can cause severe damage to life and property.

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