Some Natural Phenomena class 8 EVS by arpit

Created by :-
Arpit and Pritish9/24/2013 1Some Natural Phenomena

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Some natural
phenomena
Some Natural Phenomena9/24/2013

Content
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 Electric Charge
 Electroscope
 Lightning
 Earthquakes

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.
4Some Natural Phenomena9/24/2013

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
5Some Natural Phenomena9/24/2013

electroscope
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 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
1600

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 asSome Natural Phenomena 79/24/2013

Images for Electroscope
Some Natural Phenomena 89/24/2013

Some Natural Phenomena 9
lightning
9/24/2013

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. Some Natural Phenomena 109/24/2013

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

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

Images for fork lightning

Images for sheet lightning

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

Images of damage caused
by lightning

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 1749

Images of lightning rod

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 .

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.Some Natural Phenomena 229/24/2013

why do earthquake occur
 The earthquake occur due to these
reasons:
I. Plates slide past one another
II. Collide with one another
Some Natural Phenomena 23
New mountain
formed as the two
plates collide
On plate of earth’s
crust
Another plate of
earth’s crust
9/24/2013

Seismic zone
 The weak zone of earth’s crust are
called seismic zone

Images for earthquake

seismograph
 Seismograph is an instrument which
measures and records the magnitude of
an earth quake in terms of shock waves
it produces.

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 .

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.
Answers

Q. Match the pairs
‘A’ ‘B’
1. Earthquake Golden leaves
2. Lightning Seismograph
3. Electroscope Lightning rod

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
9/24/2013 Some Natural Phenomena 32

Some Natural
Phenomena
Made by :
Arpit and pritish

Some Natural Phenomena class 8 EVS by arpit

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