Determine the current in the 18-Ω resistor for the circuit shown in the figure assuming that the batteries are ideal.
A) 0.25 A
B) 0.50 A
C) 0.75 A
D) 1.0 A

Question

Determine the current in the 18-Ω resistor for the circuit shown in the figure assuming that the batteries are ideal. 
A) 0.25 A 
B) 0.50 A 
C) 0.75 A 
D) 1.0 A

Quizplus · Accepted Answer

The potential difference across the 18-Ω resistor can be found by subtracting the potential difference of the bottom battery from the potential difference of the top battery: 
$\Delta V = (20 V) - (10 V) = 10 V$

Using Ohm's Law, the current in the 18-Ω resistor can be found: 
$I = \frac{\Delta V}{R} = \frac{10 V}{18 \Omega} = 0.56 A$

Rounding to two significant figures, the current is approximately 0.50 A, which is answer choice B.

Determine the Current in the 18-Ω Resistor for the Circuit