Question

Capacitance and electric field of a spherical capacitor mastering physics

Answer 1

Use Gauss' Law to show the E-field anywhere between the spheres b>r>a is the same as the point charge formula;

E = kQ/r^2

where Q is the net charge on the inner sphere.

Integrate the E-field along "r" from a to b to get the Potential Difference between spheres.

V = kQINTEGRAL[dr/r^2] = kQ[(1/a) - (1/b)] = kQ[(b-a)/ab]

Use this to find Q (given V=120v) to Find parts (B) & (C) from the above E equation.

Capacitance is;

C = Q/V

=Q/kQ[(b-a)/ab]

= ab/k(b-a)

k = 1/4(pi)e(o) = 9x10^9 N-m^2/C^2