Charge is distributed uniformly along a long straight wire.The electric field 2 cm from the wire is 20 N/C.The electric field 4 cm from the wire is:
A)120 N/C
B)80 N/C
C)40 N/C
D)10 N/C
E)5 N/C

Question

Quizplus · Accepted Answer

The electric field $E$ due to a uniformly charged infinite line is inversely proportional to the distance $r$ from the wire, given by $E \propto \frac{1}{r}$. If the electric field is 20 N/C at 2 cm, at 4 cm (which is twice the distance), the electric field will be half, i.e., 10 N/C.

Charge Is Distributed Uniformly Along a Long Straight Wire