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- PHY102 Physics II © Dr.Cem Özdoğan
- Fig. 21-10 Two small conducting spheres A and B. (a) To start, sphere A is charged positively. (b) Negative charge is transferred from B to A through a connecting wire. (c) Both spheres are then charged positively.
- (1) Since the spheres are identical, connecting them means that they end up with identical charges (same sign and same amount). (2) The initial sum of the charges (including the signs of the charges) must equal the final sum of the charges.
- Reasoning: When the spheres are wired together, the (negative) conduction electrons on B move away from one another (along the wire to positively charged A— Fig. 21-10b.)
- As B loses negative charge, it becomes positively charged, and as A gains negative charge, it becomes less positively charged. The transfer of charge stops when the charge on B has increased to Q/2 and the charge on A has decreased to Q/2, which occurs when Q/2 has shifted from B to A.
- The spheres, now positively charged, repel each other.
- & (2) charge conservation Qi=Qf