Question

A positive point charge /( q /) is placed at the center of an uncharged metal sphere insulated from the ground (See attachment). The outside of the sphere is then grounded as shown. /( A /) is the inner surface and /( B /) is the outer surface of the sphere. What is the charge on A and B each?
Attachment: https://dl.dropbox.com/u/63664351/Charge.PNG

Answer 1

u kno wen grounded potential of that surface = 0

Answer 2

+ve charge at center will create negative charges all over b but it is grounded so the negative charge will be neutralized so at inner serface charge will be still +ve and at B serface will be neutral bbu tyou dont believe fools so wai tfor another reply. . .

Answer 3

@theyatin i think the +q at the center will polarize the metal sphere such that there'll be -ve charges concentrated all over A (inner surface) and equal +ve charges concentrated over B(outer surface).
now this part i'm not entirely sure of, so please feel free to correct me.
now, B is grounded. so the +ve charge on B will attract equal amt on -ve charge from the 'ground' and thus the surface B becomes neutral.
so the end answer is, A has -ve charge, while B is neutral.

Answer 4

i guess, that happens. but i'm sure, that at one point A will be -ve and B will be neutral. then because of the repulsive force between the -ve charges, they'll move to B. then because of grounding B again becomes neutral. so, we're back at square one. and then again induction takes place.
i think this process will stop when the attractive force between the +q at the center and the -ve charges on A will be stronger than the repulsive force between the -ve charges. so in the end again, A will be -ve and B will be neutral.
not too sure though. this is what i think.

Answer 5

Thanks @Vaidehi09. Yeah your answer make sense and one of the multiple-choice contain your answer.

On the other hand your answer @theyatin is not on the choice.
Here are the choices:
a) The charge on A is –q; that on B is +q.
b) The charge on B is –q; that on A is +q.
c) There is no charge on either A or B.
d) The charge on A is –q; there is no charge on B
Che. You are wrong. Again.

Answer 6

great! this confirms that my logic is correct! thanks :)

Answer 7

yup, @Vaidehi09 's logic is correct

Answer 8

@Vaidehi09
oh yup vaidehi you are right sorry for wrong interpretation. . .

Answer 9

@student92 for a fool they say once wrong is always wrong. . .