Natural PhenomenaMade by Vibhansh

Natural Phenomena

• In this presentation we are going to explain about the followings topics:

1. Introduction2. Lightning3. Earthquake4. Electrical Charge5. Transfer of charge6. Electroscope7. Seismograph

Introduction

• A natural phenomenon is not a man-made event. Examples include sunrise, weather, biological processes, physical processes, tidal flow, and include natural disasters such as electromagnetic pulses, volcanic eruptions, earthquakes.

• Various types of natural phenomena occur, including the following:

• Geological phenomena (volcanic activity and earthquakes)• Meteorological phenomena (hurricanes, thunderstorms,

and tornadoes)• Oceanographic phenomena (tsunamis, ocean

currents and breaking waves)• Exposure to forces of nature resulted in about 214,000 deaths

in 2010 up from 31,000 in 1990.

Lightning

• Lightning is a powerful sudden flow of electricity accompanied by thunder that occurs during an electric storm. The discharge will travel between the electrically charged regions. The charged regions within the atmosphere temporarily equalize themselves through a lightning flash, commonly referred to as a strike if it hits an object on the ground. It was Benjamin Franklin who first discovered that lightning was electric discharge.

Types of Lightning

• There are three primary types of lightning; from a cloud to itself (intra-cloud or IC); from one cloud to another cloud (CC) and between a cloud and the ground (CG). Although lightning is always accompanied by the sound of thunder, distant lightning may be seen but may be too far away for the thunder to be heard.

Lightning conductor

• A lightning conductor is a device used to protect buildings from damage due to lightning.

• A lightning conductor has a metallic rod. The upper end is pointed and the lower end is joined to a metal plate buried inside the ground. When lightning strikes, the electric charges pass through it to the earth without causing any damage to the building.

Protection from lightning and thunderstorm :-

a) If you are outdoors :-

i) Open vehicles like motorbikes, trucks, open cars are not safe. ii) Open fields, parks, elevated places, tall trees are not safe. iii) Carrying an umbrella is not safe. iv) If in a forest take shelter under short trees. v) If in an open field stay away from trees, poles, metallic objects. Do not lie down. Squat on the ground with hands on the knees and the head between the hands.

b) If inside the house :-

i) Lightning can strike electric wires, telephone cords and metal pipes so contact with these objects should be avoided. ii) It is safer to use mobile and cordless phones than wired phones. iii) Electrical appliances like TV, computers etc should be unplugged. iv) Bathing should be avoided to avoid contact with running water.

Earthquakes :- An earthquake is a sudden shaking or trembling of the earth caused by a disturbance deep inside the earth’s crust. Earthquakes cause damage to buildings, dams, bridges. It can cause landslides, floods and tsunamis. It can also cause damage to life and property.

The outermost layer of the earth called crust is not one piece. It is fragmented into many plates. These plates are moving continuously. When these plates brush past each other or when one plate goes under another plate due to collision, they cause disturbance and causes earthquakes.

What cause an earthquake ?

The seismic zones in India are Kashmir, Himalayas, Indo Gangetic plane, North eastern region, Kutch, Rajasthan, Andaman And Nicobar Islands some regions of South India etc. The power of an earthquake is measured on a scale called Richter scale. Very destructive earthquakes have magnitudes more than 7.5 on the Richter scale. Earthquakes produce waves on the surface of the earth called seismic waves. Seismic waves are recorded by an instrument called seismograph.

Protection from earthquakes :-Precautions during an earthquake :- a) If you are at home :- i) Take shelter under a table. ii) If you are in bed do not get up. Protect your head with a pillow. iii) Stay away from tall and heavy objects which may fall on you. b) If you are outdoors :- i) Find an open area away from buildings, trees and power lines and lie on the ground. ii) If you are in a car or bus ask the driver to slow don and don’t get out till the tremors stop.

Electric charge

• Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges – positive and negative. Positively charged substances are repelled from other positively charged substances, but attracted to negatively charged substances; negatively charged substances are repelled from negative and attracted to positive. An object will be negatively charged if it has an excess of electrons, and will otherwise be positively charged or uncharged.

Electric charge

• The SI derived unit of electric charge is the coulomb (C), although in electrical engineering it is also common to use the ampere-hour (Ah), and in chemistry it is common to use the elementary charge (e) as a unit. The symbol Q is often used to denote charge.

Charges acquired by different objects :- A glass rod rubbed with silk gets positively charged. A plastic rod rubbed with fur gets negatively charged.

Transfer of charge :- When a charged body is brought in contact with an uncharged body charges pass from the charged body to the uncharged body. This method of charging a body is called charging by contact or conduction. If a body is charged by contact it gets the same charge as the charged body. We can observe the transfer of charge by using an electroscope. If a charged plastic rod is brought in contact with an electroscope, the charges are transferred to the metal strips and they repel each other. This is because both the metal strips get the same charge and they repel each other.

Electroscope :- An electroscope is a device used to test whether an object is having electric charge or not. A simple electroscope can be made by using anempty bottle, a piece of cardboard, a paper clip andtwo small strips of aluminium foil. Pass one end ofthe paper clip through the cardboard and hang thetwo aluminiun strips from the other end. If a charged body is touched to the end of thepaper clip, the aluminium strips repel each other.

Seismograph

• Earthquakes generate seismic waves which can be detected with a sensitive instrument called a seismograph

• Advances in seismograph technology have increased our understanding of both earthquakes and the Earth itself.

• Perhaps the earliest seismograph was invented in China A.D. 136 by a m an named Choko.

Thank you

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