In a circuit, three pieces of wire labeled A, B and C are joined at a common point D. If wire B carries 1.5 mA in a direction away from D, and wire C carries current 1.3 mA toward D, what does wire A carry?
A) 0.2 mA toward D
B) 0.2 mA away from D
C) 2.8 mA toward D
D) unable to determine
E) 2.8 mA away from D

Question

Quizplus · Accepted Answer

Using Kirchhoff's current law, the sum of currents entering a junction must equal the sum of currents leaving. Since wire B carries 1.5 mA away from D and wire C carries 1.3 mA toward D, wire A must carry 0.2 mA toward D to balance the currents.

In a Circuit, Three Pieces of Wire Labeled A, B