Question

Could someone please answer this question im posting it for the second time

A spherical capacitor consists of a conducting
ball of radius 14 cm that is centered inside a
grounded conducting spherical shell of inner
radius 18 cm.
What magnitude of charge on each
is required to achieve a potential difference of 925 V between the ball and
the shell? The Coulomb constant is
8.98755 × 10^9 N.m2/C
Answer in units of C

Answer 1

capacitance of concentric spheres is given here
http://en.wikipedia.org/wiki/Capacitance

use relation C = q/V to find it out

Answer 2

I've already tried this and my answer is 6.48 and it comes wrong
do you get the same answer?

Answer 3

oh and thanks for your help