A group of students measures the currents at a junction and obtains ,
PHYSICS · Single correct · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits
Problem
A group of students measures the currents at a junction and obtains Iin=2.00A, Iout,1=0.98A, and Iout,2=0.97A. They notice that Iin is larger than the sum of the two outgoing currents by about 0.05A. All three ammeters used in the experiment are identical and have an internal resistance of 0.10Ω. Which of the following provides the best explanation for the observed discrepancy?
(a) Some current is dissipated as heat in the resistive wires, so the outgoing currents are necessarily smaller than the incoming current.
(b) The finite internal resistance of the ammeters slightly disturbs the circuit, leading to a small inequality between the entering and leaving currents.
(c) Because the ammeters have limited precision, the 0.05A difference lies within the instruments' uncertainty, and no physical imbalance needs explaining.
(d) The resistance of the connecting wires, not the ammeters, forces the battery to push extra current into the junction, so less current can flow out through the branches.