A charge - Q is uniformly distributed over a non-conducting semicircular rod of radius R. The potential at the centre is:
Answer & explanation
Correct answer: option 2
Potential at 0 due to elemental charge
$dq=\frac{1}{4 \pi \varepsilon_0} . \frac{dq}{R}$
Total Potential at 0 = $\frac{1}{4 \pi \varepsilon_0} \int\limits_0^{-Q} dq$
$= -\frac{1}{4 \pi \varepsilon_0} . \frac{Q}{R}$