State what an electric field line shows.
Determine the distance from $P$ to the point on the line joining the two charges where the electric potential is zero, given that the point charges $P$ and $Q$ are $0.120\,\text{m}$ apart as shown in Fig. 4.1. The charge of $P$ is $+4.0\,\text{nC}$ and the charge of $Q$ is $-7.2\,\text{nC}$.
State and explain, without calculation, whether the electric field strength is zero at the same point where the electric potential is zero.
The two point charges $P$ and $Q$ are $0.120\,\text{m}$ apart, as shown in Fig. 4.1.
An electron is placed at point $X$, with equal distance from both $P$ and $Q$, as shown in Fig. 4.2. On Fig. 4.2, draw an arrow showing the direction of the resultant force acting on the electron.