ELECTRIC FIELD

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an electic field converges at the origin whose magnitude is given by the expression E=100r
Nt/Coul,where r is dist.measured from origin.
a)total charge contained in any spherical vol. with its centre at origin is -ve
b)total charge contained at any spherical vol.,irrespective of the location of its centre ,is -ve
c)total charge contained in a spherical vol. of radius 3cm with its centre at origin has magnitude 3x10power(-13)C
ans a,b,c

#Physics #Electricity and magnetism

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8 Answers

1

Rohan Ghosh ·2009-03-18 08:09:37

well as it converges the charge contained in any spherical vol
has to be negative(otherwise it will diverge in case of +ve charge)
further for any spherical volume of radius r applying gauss law q/Îµ₀=-E*4Ï€r² as E=100r
we get q as a function of r

it is always negative suggesting that we have -ve charge everywhere

well one thing i must add to make it complete

let the charge at a distance x be dq

then the field contributed by it at a distance r=

kdq/r²

=kÎ»4Ï€x²/r²

apply newton leibnitz rule and then you will get lambda

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Lokesh Verma ·2009-03-18 08:10:40

This is a application of gauss law...

try to think a bit..

It is not very easy ..

but dont think anythign other than guass law.

another hint

take q(r) function of charge density with radius (origin)

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Lokesh Verma ·2009-03-18 08:11:14

oh the devil already posted it ;)

good work rohan :)

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vector ·2009-03-18 08:14:24

bt why âˆ«E.DS=E*4Î R²

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skygirl ·2009-03-18 08:20:17

becoz theya re talking about spherical volume.........

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vector ·2009-03-18 08:22:02

e is a fn of r na ???

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Lokesh Verma ·2009-03-18 08:29:25

Yes E is a function of R

but E is also given to be constant at a fixed R

so âˆ«E.DS= Eâˆ«dS = E.S

because the integral is over the whole surface..

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vector ·2009-03-18 08:31:38

kk bhaiya was thinking sumthing else thanks

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