Positive current values denote charge flowing toward a junction

PHYSICS · Single correct · AP · Physics C: Electricity and Magnetism · Electric Circuits · Electric Circuits

Problem

Positive current values denote charge flowing toward a junction. Three branches carry

I_A(t)=3.0e^{-0.5t}\;\text{A}\;(\text{toward}), \qquad I_B(t)=k e^{-0.5t}\;\text{A}\;(\text{away}), \qquad I_C(t)=2.0e^{-0.5t}\;\text{A}\;(\text{toward}).

For the junction rule to hold at every instant, what constant value must

k

have? (a)

k = 4.0

(b)

k = 5.0

(c)

k = 1.0

(d)

k = 7.0