A particle carrying charge \(q_{\mathrm{p}}=+10 \mathrm{nC}\) is located at \(y_{\mathrm{p}}=0.030 \mathrm{~m}\) on the \(y\) axis of an \(x y\) coordinate system. A nonconducting rod of length \(\ell=0.10 \mathrm{~m}\) carrying charge \(q_{\mathrm{r}}=-10 \mathrm{nC}\) lies on the \(x\) axis, extending from \(x=0\) to \(x=0.10 \mathrm{~m}\). Write an expression for the electrostatic potential for any position along the \(y\) axis.