Two conducting spheres are each 30cm in radius and each carr

Two conducting spheres are each 3.0cm in radius and each carries 0.12 microC. They are 9.0 m apart. Determine

(a)The potential on each sphere

(b)The field strength at the surface of each sphere

(c)The potential midway between the spheres

(d)The potential difference between the spheres

Solution

Since the spheres are small and widely separated, at small distances ( 9 m) they behave like isolated spheres, and at large distances they behave like two point charges.

(a) At the surface of either sphere, V= KQ/R = 9*10^9 *.12 * 10^-6 /.03 = 3.6 * 10^4 V

(b) E=V/R = 3.6*10^4/.03 =1.2 * 10^6 V/m

(c) Midway between the spheres, the potential from each one is the same, so

V= 2*KQ/R = 2*9*10^9 *.12 *10^-6 /4.5 =480V

(d) The spheres are at the same potential, so the difference is zero.