Class 8th EVS lesson contains about electroscope lightning earthquake positive charge
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PHENOMENACreated by :-
Arpit and Pritish9/24/2013
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Some natural phenomena
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Content Electric Charge
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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 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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Q. Match the pairs
‘A’ ‘B’1. Earthquake Golden
2. Lightning Seismograph
3. Electroscope Lightning rod
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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