IIT JEE , AIEEE Forum - Physics , Electricity

mukulss

a conducting sphere of a radius a has charge Q on it.
it is enclosed by an neutral conducting concentric spherical shell havin inner radius 2a and outer radius 3a.

find the electroststic energy of the system

please reply

mukulss

hello???

bhuvankar

is it 11/12 KQ2??? (Q2---------Qsquare)

mukulss

no man it is 5kQ^2/12a

plaese nyone see to it???

mukulss

right answers??????

feynmann

See the electric field at a distance r from the origin is given by

E = K Q / r^2

Now energy density U = 1/2

o E^2

So the total energy is

U* 4 pi r^2 dr ( from to 3a ) + _{U *4 pi r^2 dr ( from a to 2a )}

_{Carrying out this integral and noting that 4 pi o = 1/K , we get total energy = 5 / 12 K Q ^2 /a}

We are breaking the limit in this fashion because we know that E inside any conducting shell = 0 in the electrostatic case .

mukulss

thnx a lot feymann

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