Question

If the potential (relative to infinity) due to a point charge is V at a distance R from this charge, the distance at which the potential (relative to infinity) is 2V is
A. 4R
B. 2R
C. R/2.
D. R/4

Answer 1

Answer:

R/2

Explanation:

The potential at a distance r is given by :

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

Where

k is electrostatic constant

q is the charge

The potential (relative to infinity) due to a point charge is V at a distance R from this charge. So,

$\dfrac{V_1}{V_2}=\dfrac{r_2}{r_1}$

Put all the values,

$\dfrac{V}{2V}=\dfrac{r_2}{R}\\\\\dfrac{1}{2}=\dfrac{r_2}{R}\\\\r_2=\dfrac{R}{2}$

So, the distance at which the potential (relative to infinity) is 2V is R/2.