A 4.0-Ω resistor is connected to a 12-Ω resistor and this combination is connected to an ideal dc power supply with voltage V as shown in the figure. If the total current in this circuit is I = 2.0 A, what is the value of voltage V?
A) 2.0 V
B) 3.0 V
C) 6.0 V
D) 1.5 V
E) 8.0 V

Question

A 4.0-Ω resistor is connected to a 12-Ω resistor and this combination is connected to an ideal dc power supply with voltage V as shown in the figure. If the total current in this circuit is I = 2.0 A, what is the value of voltage V? 
A) 2.0 V 
B) 3.0 V 
C) 6.0 V 
D) 1.5 V 
E) 8.0 V

Quizplus · Accepted Answer

First, we can use Ohm's Law to find the voltage drop across each resistor:
V = IR

For the 4.0-Ω resistor: 
V1 = IR = (2.0 A)(4.0 Ω) = 8.0 V

For the 12-Ω resistor: 
V2 = IR = (2.0 A)(12 Ω) = 24 V

The total voltage drop across both resistors is equal to the voltage of the power supply, so:

V = V1 + V2 
V = 8.0 V + 24 V 
V = 32 V

Therefore, the answer is C) 6.0 V.

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