Post on 29-Jul-2015
transcript
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Some natural phenomenaON A STORMY NIGHT,WE OFTEN HEAR A
LOUD NOISE OF THUNDER AND SEE A BLUISH
-WHITE FLASH OF LIGHT IN THE SKY.HAVE YOU EVER WONDERED WHAT
THESE ARE AND HOW THEY ARE CAUSED?THESE ARE SOME NATURAL PHENOMENA THAT OCCUR IN NATURE. SOME OTHER
NATURAL PHENOMENON ARE EARTHQUAKES ,TSUNAMI,ETC.
LET US READ ON TO LEARN MORE ABOUT LIGHTNING & EARTHQUAKES.LET US
ALSO FIND OUT HOW ELECTRIC CHARGES ARE LINKED WITH LIGHTNING.
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Electric chargesELECTRIC CHARGE IS THE PHYSICAL PROPERTY OF MATTER THAT CAUSES IT TO EXPERIENCE A FORCE WHEN CLOSE TO OTHER ELECTRICALLY CHARGED
MATTER. THERE ARETWOTYPES OF ELECTRICCHARGES 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 OFELECTRONS, AND WILL OTHERWISE BE POSITIVELY CHARGED OR
UNCHARGED.
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Charging a body
An electrically neutral object can be charged by various
methods.The various methods are:-
Charging by frictionCharging by conductorsCharging by induction
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WE CAN TRANSFER ELECTRIC CHARGE FROM A CHARGED
OBJECT TO A NEUTRAL OBJECT THROUGH A METAL
CONDUCTOR.A DEVICE CALLED ELECTROSCOPE WHICH IS
USED TO DETECT AND MEASURE ELECTRIC CHARGE IS
BASED ON THIS PRINCIPLE.
Transfer of charges:-
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THIS STREAK OF BRIGHT LIGHT IS
KNOWN AS LIGHTNING AND THE PROCESS IS CALLED
ELECTRIC DISCHARGE.
Lightning:-
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LIGHTNING CONDUCTOR A STRIP OF METAL, GOING FROM
THE HIGHEST POINT OF A BUILDING TO THE GROUND, THAT PREVENTS LIGHTNING
FROM DAMAGING THE BUILDING BY TAKING THE
ELECTRICITY TO THE GROUND BEFORE IT CAN REACH A
DANGEROUS LEVEL
Lightning conductors:-
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spikesStorm cloud
Tall building
Stream of
positive ions
Electrons repelled
to the earth
Copper strip
Diagram Lightning conductors:-
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Safety during lightning :-
DO NOT REMAIN IN AN OPEN PLACE.
STAY AWAY FROM WATER.
DO NOT STAND UNDER A TREE
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AN EARTHQUAKE (ALSO KNOWN AS A QUAKE, TREMOR OR
TEMBLOR) IS THE RESULT OF A SUDDEN RELEASE OF ENERGY IN
THE EARTH'S CRUST THAT CREATES SEISMIC WAVES. THE
SEISMICITY, SEISMISM OR SEISMIC ACTIVITY OF AN AREA REFERS TO THE FREQUENCY, TYPE AND SIZE OF EARTHQUAKES EXPERIENCED
OVER A PERIOD OF TIME.
Earthquakes :-
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Structure of the earth :-THE EARTH CONSISTS OF THREE PARTS:-CRUST= IT IS THE OUTERMOST SOLID
SHELL OF THE EARTH.IT IS OF NON-UNIFORM THICKNESS AND IS THINNER AT THE OCEAN FLOOR. IT IS COMPOSED OF A
VARIETY OF ROCKS.MANTLE=IT IS LIES JUST BELOW THE CRUST.
IT CONSISTS OF SEMI-SOLID ROCKS,IRON,MAGNESIUM AND CALCIUM.
CORE=IT IS THE INNERMOST PART OF THE EARTH AND IS DIVIDED INTO TWO SECTIONS
THE OUTER CORE CONTAINS IRON AND NICKEL IN MOLTEN STATE.THE INNER CORE IS BELIEVED TO BE MADE OF COMPRESSED IRON
AND NICKEL IN SOLID FORM.
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AN EARTHQUAKES IS A SUDDEN
MOVEMENT OR A DISTURBANCE IN
THE LITHOSPHERE.
Occurrence of earthquakes :-
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Measuring intensity of earthquakes :-
THE INSTRUMENT USED TO MEASURE SEISMIC WAVES IS CALLED A SEISMOGRAPH. THE
RECORD OF THE SEISMOGRAPH ON THE
GRAPH PAPER IS CALLED SEISMOGRAM.
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Protection against earthquakes :-WHILE CONSTRUCTING A BUILDING, CONSULT A QUALIFIED ARCHITECT AND CIVIL ENGINEER FOR TIPS ON HOW TO MINIMIZE THE EFFECT OF
AN EARTHQUAKES ON THE STRUCTURE.
REPAIR ANY CRACKS IN THE WALLS OR CEILINGS.
KEEP FIRE FIGHTING EQUIPMENTS HANDY AS SOME BUILDINGS MAY
CATCH FIRE DUE TO AN EARTHQUAKE.