Logic Question (involves static electricity)

[qIat]

MS = metallic sphere with charge Q

You are given 3 identical conducting spheres, A, B, C

They can be moved and grounded

With q<Q, how do you give them charges q, -q/2, and -q/2?

You are wearing rubber gloves so you do not discharge anything.

Winner gets a cookie.

 

[Eli]

I don't even know where to begin heh.

I wish I was better at math. 🙁

 

[dude]

If all the spheres are identical, how can you make one take more charge than the other spheres? Plus, once any of the spheres touch Q, they will discharge Q. If they touch each other, they will discharge themselves and charge their identical selves.

Is thhis physics or math? ;|

 

[randal]

that's not a logic question, that's a homework question.

 

[qIat]

Originally posted by: dude
If all the spheres are identical, how can you make one take more charge than the other spheres? Plus, once any of the spheres touch Q, they will discharge Q. If they touch each other, they will discharge themselves and charge their identical selves.

Is thhis physics or math? ;|

A little of both 🙂

You make one take more charge than the others because Q is only the starting charge of MS; after A touches Q, it will have, say, Q/2 and the MS will have Q/2 as well (or whatever proportion you like). After B touches Q, it will have Q/4 and MS will have Q/4.

 

[esun]

I think this is right:

First, line up spheres A and C so they are touching. Then move MS to one side of the row, but not touching any of the spheres (like this: (MS) (A)(C)). This will cause a charge -q to be attracted into sphere A and a charge +q into sphere C. Now, touch sphere A and sphere B together and the extra charge will distribute among the two spheres, causing sphere A and B to have charge -q/2 each, and sphere C to have charge +q.


EDIT: Slight correction of reference (some reason I referred to the sphere MS as Q).

 

[qIat]

Originally posted by: esun
I think this is right:

First, line up spheres A and C so they are touching. Then move MS to one side of the row, but not touching any of the spheres (like this: Q AC). This will cause a charge -q to be attracted into sphere A and a charge +q into sphere C. Now, touch sphere A and sphere B together and the extra charge will distribute among the two spheres, causing sphere A and B to have charge -q/2 each, and sphere C to have charge +q.

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Click on the link, you get the cookie.

This is all made possible by the way the valence electrons move in a conductor.

 

[esun]

w00t I win