Question

Choose the graph that represents the variation of potential $\left(V\right)$ versus distance from the centre of ring along its axis $\left(r\right)$ for a uniform ring of change $Q$.

• A.
• B.
• C.
• D.

Answer 1

The correct option is C


Potential at point $\text{P}$ at distance $r$ from the centre of a ring of charge $Q$:

$V_P=\frac{KQ}{\sqrt{R^2+r^2}}$

At centre $r=0$,

$\Rightarrow V_P=\frac{KQ}{R}$

So, maximum potential exists at the centre of the ring.

Similarly, as $r\to \infty$

$\Rightarrow V_P=0$

On plotting the above result, we get the graph as shown below


Hence, option (c) is the correct answer.