Question

A wire is bent into a circle of radius \[R = 10\ \text{cm}\] carrying a uniformly spread charge \[q = 250\ \mu\text{C}\]. The electric potential at the centre of the circle is:

Options

• \[2.25 \times 10^9\ \text{volt}\]

• \[2.25 \times 10^5\ \text{volt}\]

• \[2.25 \times 10^7\ \text{volt}\]

• \[9 \times 10^7\ \text{volt}\]

Answer 1

Since every point on the ring is at the same distance (the radius) from the centre, the ring can be treated like a point charge for the potential at the centre: \[V=\frac{1}{4\pi\varepsilon_0}\frac{q}{r}=9\times10^9\times\frac{250\times10^{-6}}{10^{-1}}=2.25\times10^7\ \text{volt}\].