In a diagram of charges and electric field lines charge $Q _ { 1 }$ has twelve field lines going outward from it and charge $Q _ { 2 }$ has three field lines going into it.If one of the charges is 100 nC,what is the other one?
A)25 nC
B)100 nC
C)-25 nC
D)-100 nC
E)Both answers b and c can be correct.

Question

Quizplus · Accepted Answer

The number of field lines is proportional to the magnitude of the charge. Since $Q_1$ has 12 lines and $Q_2$ has 3 lines, the magnitude of $Q_2$ is one-fourth that of $Q_1$. If one charge is 100 nC, the other must be 25 nC. Since field lines go into $Q_2$, it is negative, so $Q_2 = -25 \text{ nC}$.

In a Diagram of Charges and Electric Field Lines Charge Q1Q _ { 1 }Q1​

In a Diagram of Charges and Electric Field Lines Charge $Q _ { 1 }$