Answer:
it will take for the sphere to increase in potential by 1500 V, 503.71 s.
Explanation:
The charge on the sphere after t seconds is:
q = (1.0000049 - 1.0000000) t = 0.0000049 t
The voltage on the surface is
V = k * = k 0.0000049 t / R
solve for t
t = (R*V) / (0.0000049 k) = (0.12 * 1500) / (0.0000049 * ) = 503.71 s