Electrostatics, electrons, protons, and all that good stuff

[Creative-Amy]

Electrostatics, electrons, protons, and all that good stuff:)

Homework Statement

Two uncharged metal balls, X and Y, stand on glass rods, are in touch as shown to the right. A third ball Z, carrying a positive charge, is brought near the first two (closer to Y than X). Then the first two balls are separated from each other, and ball Z is finally removed. What are the charges (if any) on each of the balls?

Homework Equations

none

The Attempt at a Solution

After applying my new knowledge of electrostatics I concluded that x is positive and y is neutral, but I'm not sure so any help would be great!

 

[Delphi51]

I would say partly right.
If I am visualizing it correctly, the positive charge induces a charge separation on the xy pair.
It pushes positive charges away and pulls negative ones closer. That should leave a net charge on x and on y. In any case the total charge on x plus y must be zero because nothing has touched the pair of them to add any charge.

 

[Creative-Amy]

That is true...so no change other than a shift in negative electrons should be observed and they should both remain neutral?

I just want to get this straight, whenever the y ball has been induced to be positive by the z ball(-) and x is in touch to y while this is occurring nothing should change?

 

[Delphi51]

There is a change! Charge is moved from one ball to the other. Electrons are pulled toward the positive charge - they move from the ball that is further away to the ball that is closer to the positive charge. This leaves each of the balls with a net charge. The total of the charges on the two balls is zero because charges are only moved, not created.

 

[Creative-Amy]

Oh ok that makes sense, thank you!:)