Three resistors with resistances of 2.0 Ω,6.0 Ω,and 12 Ω are connected across an ideal dc voltage source V as shown in the figure.If the total current through the circuit is I = 2.0 A,what is the applied voltage V?
A)6.0 V
B)3.0 V
C)2.0 V
D)2.7 V
E)1.5 V

Question

Three resistors with resistances of 2.0 Ω,6.0 Ω,and 12 Ω are connected across an ideal dc voltage source V as shown in the figure.If the total current through the circuit is I = 2.0 A,what is the applied voltage V? 
A)6.0 V 
B)3.0 V 
C)2.0 V 
D)2.7 V 
E)1.5 V

Quizplus · Accepted Answer

Using Ohm's law, the voltage across each resistor can be calculated:
V(2 Ω) = (2 A)*(2 Ω) = 4 V
V(6 Ω) = (2 A)*(6 Ω) = 12 V
V(12 Ω) = (2 A)*(12 Ω) = 24 V

The total voltage across the circuit is:
V = V(2 Ω) + V(6 Ω) + V(12 Ω) = 40 V

Therefore, the applied voltage is V = 2.7 V (closest to the calculated value). So the answer is D.

Three Resistors with Resistances of 2