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Hi.
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In this question it is given that a charge of a magnitude 15 microculum is uniformly distributed over a spherical shell.
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Its inner radius r1 and outer radius r2 are given.
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The question is to find the electric field at a distance r of 12 centimetre from its center.
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Electric field is given by the formula.
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A is equal to kq by r square.
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The charge q can be written as the product of volume v into surface charge density sigma, where v the volume has the formula as 4 by 3 pi r cubed.
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In our case, it is 4 by 3 pi pi into r cube minus r1 cube.
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Substitating the values now, 4 by 3 into pi 3 .14 into r cube that is point 1 to the whole cube minus r1 .1 .1 the whole cube.
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Simplifying we get the answer for volume as 3 .05 into 10 to the power minus 3 meter cube.
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Doing similarly for sigma the charge density which has a general formula as charge by unit volume, q by v.
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Cube is 15 microculum 15 into 10 to the power minus 6 divided by volume here will be 4 by 3 5 into r2 cube minus r1 cube the difference in the cubes of their outer and inner radia...