Answer to Question #318050 in Physics for biA

Question

Sphere A has charge of +10.0 C. It is brought in contact with a neutral sphere B and then separated. Find the final charges on spheres A and B if

a. The spheres have equal radius and

b. If the radius of sphere B is twice the radius of sphere A

Answer 1

The law of conservation of charge says

$$q_A+q_B=q_A'+q_B'$$

(a) $q_B'=q_A'$

$$q_A=q_A'+q_B'=2q_A'$$

$$q_A'=q_B'=q_A/2\\ =+10.0/2=+5.00\:\rm C$$

(b) $q_B'=2q_A'$

$$q_A=q_A'+q_B'=3q_A'$$

$$q_A'=q_A/3\\ =+10.0/3=+3.33\:\rm C$$

$$q_B'=+6.67\:\rm C$$