The current in the circuit shown is
A) 1.0 A
B) 0.65 A
C) 0.44 A
D) 0.22 A
E) None of these is correct.

Question

The current in the circuit shown is
A) 1.0 A 
B) 0.65 A 
C) 0.44 A 
D) 0.22 A 
E) None of these is correct.

Quizplus · Accepted Answer

The current through a series circuit is constant, therefore the current at all points in the circuit is the same. Using Ohm's law, the total resistance of the circuit can be found:
R = R1 + R2 + R3 = 5 + 10 + 5 = 20 ohms
Then, using Ohm's law again: 
V = IR
10 = I(20)
I = 0.5 A
Therefore, the current in the circuit is 0.5 A or 500 mA. However, the ammeter is located in the middle of the circuit, where it is measuring the current through R2 and R3. 
Using Ohm's law on this part of the circuit: 
V = IR
5 = I(R2 + R3)
5 = I(10)
I = 0.5 A/2 = 0.25 A or 250 mA (this is the current passing through R2 and R3). 
Therefore, the correct answer is choice C, 0.44 A (rounding to two significant figures).

The Current in the Circuit Shown Is