Could we maybe add some numbers here? Like R=0.1 cm and Q=5*10^-7 C? Could do this as a charged balloon or something.

Suppose we have a positively charged balloon with total charge $Q=5\cdot 10^{-7} \text{ C}$. What is the electric potential at a point $P$, which is a distance $R=50 \text{ cm}$ from the center of the balloon? A diagram below shows a rough sketch.

• The charge with value $Q$ is a point charge.
• The point $P$ is a distance $R$ away from the point charge.

• The electric potential at $P$.

• The electric potential at $P$ is due entirely to the point charge.
• The electric potential infinitely far away from the point charge is $0 \text{ V}$.

• The electric potential from the point charge can be written as $$V = \frac{1}{4\pi\epsilon_0}\frac{q}{r},$$ where $q$ represents our charge ($Q$) and $r$ is our distance ($R$).

The electric potential at $P$ is given by \begin{align*} V &= \frac{1}{4\pi\epsilon_0}\frac{q}{r} \\ &= \frac{1}{4\pi\epsilon_0}\frac{Q}{R} \\ \end{align*}