Worked example: An isolated neutral metal sphere A is touched with a positively charged metal sphere B (also isolated), then separated. Afterwards B is touched to an identical neutral metal sphere C. What are the final charges if B initially carried +12 nC? Step 1: When two identical conductors touch, charge shares equally. A and B touch: total charge = 0 + 12 = +12 nC, so each gets +6 nC. Step 2: Now B (+6 nC) touches neutral C: total = +6 nC, shared equally, so B and C each end with +3 nC. Final: A = +6 nC, B = +3 nC, C = +3 nC. Step 3 (concept check): If A had been an insulator instead of a conductor, the charge would NOT spread over A — only the tiny contact spot would gain charge, because insulators cannot move charge across their body. This is exactly why the equal-sharing rule applies only to conductors.