## Electric potential inside conductor derivation

Hey, i have this question:
The electric potential inside a charged spherical conductor of radius R is given by V = keQ/R and outside the conductor is given by V = keQ/r. Using E=-dV/dr, derive the electric field inside this charge distribution.

Alright, so I started to find the derivative of the formula for the potential outside the conductor, however Ke, and Q are constants. Therefore E=-KeQ. Subbing into the first formula, to solve for the potential inside the sphere, i got E= -V/R. Sounds good?
well, when i submit my answer, it says it needs a numerical answer, did i go wrong somewhere?
Brent
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 R is constant and r is variable.... the E field is dV/dr whereas V is constant inside the conductor, therefore, the answer is zero...
 Convince yourself of the physical implications of what vincentchan said, by using Gauss's law and intuition. (a) what should the electric field inside and outside such a body be? (b) what should the electric potential inside, on the surface and outside such a body be? are (a) and (b) mutually consistent? If so, why? And if not, why not (in your answer that is)?