Question

what is the electric potential 1.0m m assuming that the potential is zero at r=infinite

Answer 1

Let the charge is q,

so electric potential at the distance r is

$V=\frac{q}{4\pi \epsilon_o r}$

if r is infinite then potential $(V)=\frac{q}{4\pi \infty}=0$

Now, if$( r)=1.00mm=1.0\times 10^{-3}m$

$V=\frac{q}{4\pi \epsilon_o\times 1.0\times 10^{-3}m}$

$=\frac{q\times 10^{3}}{4\pi \epsilon_o}$