What is the approximate radius of an equipotential spherical surface of 100 V about a point charge of +45 nC if the potential at an infinite distance from the surface is zero?
A)1.0 m
B)2.1 m
C)3.0 m
D)4.5 m
E)4.0 m

Question

Quizplus · Accepted Answer

The potential $V$ at a distance $r$ from a point charge $q$ is given by the formula $V = \frac{kq}{r}$, where $k$ is Coulomb's constant ($8.99 \times 10^9 \, \text{N m}^2/\text{C}^2$). Given $V = 100 \, \text{V}$ and $q = 45 \, \text{nC} = 45 \times 10^{-9} \, \text{C}$, we can solve for $r$:$$100 = \frac{(8.99 \times 10^9)(45 \times 10^{-9})}{r}$$Solving for $r$, we find $r \approx 4.0 \, \text{m}$.

What Is the Approximate Radius of an Equipotential Spherical Surface