Question

Two small charged spheres are placed so that their centres are 12.5 cm apart. The force of repulsion exerted by one charged sphere on the other is 0.432 N. If the charge on one of the spheres is +2.50 x 10-7 C, then the charge on the other sphere is
Select one:
a. +3.00 x 10-6 C
b. +2.40 x 10-5 C
c. +2.40 x 10-3 C
d. +3.00 x 10-2 C

Answer 1

F = k Q1 Q2 /d^2 (Coulomb's Law)
.432 = 9*10^9 * 2.5*10^-7 Q2/.125^2
Q2 = 3 * 10^-6

Answer 2

By the way I call that Physics :)