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SOME NATURAL PHENOMENA Created by :- Arpit and Pritish 9/24/2013 1 Some Natural Phenomena
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Some Natural Phenomena class 8 EVS by arpit

Aug 23, 2014

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Science

Arpit Lekurwale

Class 8th EVS lesson contains about electroscope lightning earthquake positive charge
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Page 1: Some Natural Phenomena class 8 EVS by arpit

Some Natural Phenomena 1

SOME NATURAL

PHENOMENACreated by :-

Arpit and Pritish9/24/2013

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Some Natural Phenomena 2

Some natural phenomena

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Content Electric Charge

Electroscope

Lightning

Earthquakes

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Electric Charge It was discovered about 2500 yrs

ago It was discovered by a Greek

scientist called Thales. An object without any charge is

called uncharged object And the object with an electric

charge is called charged object The process of giving charge is

called charging the object.

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Electric Charge Twentieth-century experiments

 demonstrated that electric charge is quantized.

The charging of an object by rubbing it with another object is charging by friction.

The electric charges generated by rubbing (or friction) are static electric charges.

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electroscope A device used for detecting

electric charge on a object  It was the first

electrical measuring instrument

The first electroscope, a pivoted needle called the versorium

It was invented by British physician William Gilbert around 16009/24/2013

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electroscope The gold-leaf electroscope was

developed in 1787 by British clergyman and physicist Abraham Benet

The electroscope can also be charged without touching it to a charged object, by electrostatic induction

The electric potential or voltage of an object equals its charge divided by its capacitance, so electroscopes can be regarded as crude voltmeters

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Images for Electroscope

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lightning

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Lightning The bright flash of light which we see in the

clouds is called lightning. There are three types of lightning:

1. Cloud to itself (intra cloud or sheet lightning)2. From one cloud to another (Cloud to cloud or

CC)3. Cloud to the ground (CG)

The electric nature of lightning was established by Benjamin Franklin

 Lightning occurs approximately 40–50 times a second worldwide, resulting in nearly 1.4 billion flashes per year.

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lightning  It is a massive electrostatic discharge

between electrically charged regions within clouds , or between a cloud and the Earth's surface.

The lightning which usually occurs within the cloud in the sky is called ‘sheet lightning’

And the lightning which usually occurs between a cloud and the earth or the objects on it is called 'fork lightning’.

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lightning The science of lightning is

called fulminology. The fear of lightning is

called astraphobia. Lightning is not distributed evenly

around the planet. About 70% of lightning occurs over

land in the tropics where atmospheric convection is the greatest

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Pictures for lightning

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Images for fork lightning

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Images for sheet lightning

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dangers of lightning When a lightning strikes the earth

it causes a lot of damage to the property (buildings ,etc.)

Although lightning is an beautiful phenomena but it is very dangerous

Before 4 days lightning was stroked 3 times in lake forest at Chicago

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Images of damage caused by lightning

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Lightning rod Lightning conductor is a device

used to protect a building from the effects of lightning

The function of lightning conductor is to conduct any lightning strikes safely to the earth(without causing any damage to the building).

The lightning rod was invented by Benjamin Franklin in North America in 17499/24/2013

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Images of lightning rod

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Measures to protect ourselves from lightning Don't take shelter in open space, a house

or a building will be a safe place Open vehicles like motorbikes ,scooters

,tractors are not safe We should avoid raising umbrella over

head during lightning, as because it lightning may strike at the top of the umbrella .

TV antennas are more prone to lightning, so we should switch off our TV sets during lightning .

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earthquake The sudden shaking (or

trembling) of the earth’s surface which lasts for a short time is called earthquake .

It is a destructive natural phenomena which cannot be predicted in advance

Earthquakes are measured using observations from seismometers.

Earthquakes can also cause floods , landslides ,tsunamis.

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why do earthquake occur The earthquake occur due to

these reasons:I. Plates slide past one anotherII. Collide with one another

New mountain formed as the two plates collide

On plate of earth’s crust

Another plate of earth’s crust

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Seismic zone The weak zone of earth’s crust

are called seismic zone

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Images for earthquake

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seismograph Seismograph is an instrument which

measures and records the magnitude of an earth quake in terms of shock waves it produces.

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Q. Fill in the blanks

1. Like charges ; unlike charges .

2. The sudden shaking of land is called an .

3. the bright flash of light that we see in the sky is called .

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1. Like charges repel ; unlike charges attract

2. The sudden shaking of land is called an earthquake.

3. the bright flash of light that we see in the sky is called lightning.

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Answers

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Q. Match the pairs

‘A’ ‘B’1. Earthquake Golden

leaves

2. Lightning Seismograph

3. Electroscope Lightning rod

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conclusion

From this presentation we learnt about the various natural phenomena and there effects and how they are caused

Although some phenomena are beautiful, but they are dangerous

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Some Natural PhenomenaMade by :

Arpit and pritish