AP 8th Class Physical Science Notes Chapter 9 Some Natural Phenomena
→ Crust : The outermost layer of the earth is called the crust.
→ Discharge : Process of the flow of electric charge from one body to another.
→ Earth’s Plates : The fragments of the outermost layer of the earth are called plates.
→ Earthquake : An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time, caused by a disturbance deep inside the earth’s crust.
→ Electroscope : The device that can be used to test whether an object is carrying a charge or not is known as an electroscope.
→ Lightning : Lightning is a natural phenomenon caused by the accumulation of charges in the clouds.
→ Lightning Conductor : A lightning conductor is a device used to protect buildings from the effect of lightning.
→ Negative Charge : It is a type of charge that forms on an object by gaining electrons while rubbing with another object.
→ Positive Charge : It is a type of charge that forms on an object by losing electrons while rubbing with another object.
→ Richter Scale : The power of an earthquake is expressed in terms of a magnitude on a scale called the Richter scale.
→ Seismograph : A seismograph is an instrument to record seismic waves.
→ Thunder : The loud noise produced when discharge takes place in the air between clouds is called thunder.
→ Thunderstorm : A thunderstorm is a storm with lightning and thunder.
→ Transfer of Charge : The flow of charged particles from one object to another object is called the transfer of charge.
→ Tsunami : Tsunami is a natural phenomenon caused by an earthquake in the sea.
→ Tremor : The shaking of the earth is called a fremor.
→ Lightning is caused by the accumulation of charges in the clouds.
→ When a plastic refill is rubbed with polythene, it acquires a small electric charge. These objects are called charged objects.
→ A charged balloon repelled a charged balloon.
→ A charged refill repelled a charged refill.
→ A charged balloon attracted a charged refill.
→ The electrical charges generated by rubbing are static.
→ The device that can be used to test whether an object is carrying a charge or not is known as an electroscope.
→ Electrical charge can be transferred from a charged object to another through a metal conductor.
→ The process of transferring charge from a charged object to the earth is called earthing.
→ Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current.
→ A lightning strike could destroy life and property.
→ During lightning and thunderstorm, no open place is safe.
→ A lightning conductor is a device used to protect buildings from the effect of lightning.
→ If a thunderstorm occurs there is always a possibility of lightning and cyclones accompanying it.
→ Earthquakes can cause damage to human life and property on a huge scale.
→ An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time. It is caused by a disturbance deep inside the earth’s crust.
→ Earthquakes occur all the time, all over the earth.
→ The fragment of the outermost layer of the earth is called a plate. These plates are in continual motion.
→ The boundaries of the plates are the weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.
→ The power of an earthquake is expressed in terms of a magnitude on a scale called the Richter scale.
→ The tremors produce waves on the surface of the earth. These are called seismic waves. The waves are recorded by an instrument called the seismograph.
→ An earthquake of magnitude 6 has thousand times more destructive energy than an earthquake of magnitude 4.
→ Earthquakes cannot be predicted.
→ An earthquake measuring 7 or more on the Richter scale can cause severe damage to life and property.