Question

A metal sphere, X, has an initial net charge of −6 × 10−6 coulomb and an identical sphere, Y, has an initial net charge of +2 × 10−6 coulomb. The spheres touch each other and then separate. What is the net charge on sphere X after the spheres have separated?

Answer 1

When the two spheres touch each other, part of the charge recombine together. The part of charge that recombines is the excess of positive charge on sphere Y,
`Q_y = +2 \cdot 10^(-6)C`, that recombines with an equivalent charge of
`-2 \cdot 10^(-6)C` located on sphere X. As a result, the total charge remained on the two spheres is the excess of negative charge remained on sphere X:

`Q=-4 \cdot 10^(-6)C`
Since the two spheres are identical, they have same capacity, so this charge will now redistribute equally on the two spheres: therefore, at the end, each sphere will have

`(Q)/(2)=-2 \cdot 10^(-6) C`