What is the magnitude of the potential difference across the 20-Ω resistor?
A)3.2 V
B)7.8 V
C)11 V
D)5.0 V
E)8.6 V

Question

What is the magnitude of the potential difference across the 20-Ω resistor? 
A)3.2 V 
B)7.8 V 
C)11 V 
D)5.0 V 
E)8.6 V

Quizplus · Accepted Answer

We can use Kirchhoff's loop rule to find the potential difference across the 20-Ω resistor. Starting from the upper left corner of the circuit and moving clockwise, we encounter a voltage drop of 6 V across the 4-Ω resistor, followed by another voltage drop of 12 V across the 8-Ω resistor. Finally, we encounter a voltage drop across the 20-Ω resistor that we are interested in, which we will call V. We then encounter a 10-V battery as we complete the loop. Applying Kirchhoff's loop rule, we have:

-6 V - 12 V - V + 10 V = 0

Simplifying, we get:

V = 8 V

Therefore, the potential difference across the 20-Ω resistor is 8 V, which corresponds to choice (B).

What Is the Magnitude of the Potential Difference Across the 20-Ω