Question

Estimate the potential at 2cm from a proton and find the potential difference between two points that are 2cm and 4cm from a proton.

Answer 1

Answer

Potential difference due to a point charge is given

$V=\frac{kq}{r}$

the potential at 2cm from a proton

$V=\frac{kq}{r}=\frac{9\times10^9\times1.6\times10^{-19}}{0.02}$

$=72\times10^{-9}V$

the potential at 4cm from a proton

$V'=\frac{kq}{r}=\frac{9\times10^9\times1.6\times10^{-19}}{0.04}$

$=36\times10^{-9}V$

the potential difference between two points that are 2cm and 4cm from a proton is given

$\Delta V=V-V'$

$=(72-36)\times10^{-9}V\\=36\times10^{-9}V$