
The diagram below shows electric field lines around two isolated point changes \(\mathrm{P}\) and…

- \(\mathrm{Q}\) is smaller charge than \(\mathrm{P}\) because \(\mathrm{X}\) is
closer to P than \(\mathrm{Q}\) - Field strength is always proportional to the distance from \(X\)
- The potential at \(Q\) is less than the potential at \(P\)
- The field lines show that charges are positive
Solution

From the diagram, we conclude that (1) \(\mathrm{Q}\) is larger charge because \(\mathrm{X}\) is closer to \(\mathrm{P}\) than Q. When
\(E_{P}=E_{Q}=\frac{q_{P}}{4 \pi \varepsilon_{0} r_{P}^{2}}=\frac{q_{Q}}{4 \pi \varepsilon_{0} r_{Q}^{2}} \therefore \frac{q_{P}}{q_{Q}}=\left(\frac{r_{P}}{r_{Q}}\right)^{2}\)
Since \(r_{Q} > r_{p}\), then \(q_{Q} > q_{p} .(2)\) The field strength is always proportional to the inverse squared distance from \(X\) as it can be readily seen from the expression in \((1),(3) .\) The potential at \(\mathrm{P}\) or \(\mathrm{Q}\) is infinitely large since the potential at the location of an isolated charge is theoretically infinite. (4) Both charges are positive since the field lines are radially outward from the charges. Hence (d) is correct. It may additionally be noted ~
Asked in: JEE Mains - Electrostatics - Chapter Test