Conservation of energy between two charged sheres

AI Thread Summary
The discussion centers on the conservation of energy between two charged spheres, one insulating and one conducting. For insulating spheres, the potential energy change (delta-U) is calculated based on their separation, indicating that some electric potential energy remains when they touch. In contrast, when conducting spheres touch, they reach electrostatic equilibrium, resulting in zero potential energy and potentially greater final velocities due to charge redistribution. The instructor noted that the electric field between conducting spheres increases, leading to a higher final voltage, complicating the energy equation. The key takeaway is that the behavior of charged spheres differs significantly based on their insulating or conducting properties.
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conservation of energy between two charged spheres

We are given two insulating spheres with charges q1 and -q2 separated by a distance d. Using concepts of conservation of energy and linear momentum, I solved for the velocity of each sphere at the point of contact.
We are then asked if the spheres were conducting, would the final velocity be greater. delta-U for the insulating spheres is U-final minus U- initial = Keq1q2(1/(r1+r2) - 1/d)) meaning there is some electric potential energy remaing, because the center of spheres are still separated.
But when the two conducting spheres touch, they are in electrostatic equilibrium, right? So there is no more potential energy, correct? How do I write an expression for the delta-U in this case? I should get a greater value, right?
 
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In that case, U-final would be 0 wouldn't it?
 
Talked to my instructor today. He said that when the spheres are conducting, the charges migrate across the surface increasing the magnitude of E in between, hence higher V-final. He also said its not a simple equation anymore, but we weren't really asked for one, just to reason that out.
 
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