A 3.0-Ω resistor is connected in parallel with a 6.0-Ω resistor. This combination is then connected in series with a 4.0-Ω resistor. The resistors are connected across an ideal 12-volt battery. How much power is dissipated in the 3.0-Ω resistor? Group of answer choices
a. 12 w
b. 2.7 w
c. 6.0 w
d. 5.3 w

To solve this problem we must find the values of the equivalent resistances in both section 1 and section 2. Later we will calculate the total current and the total voltage. With the established values we can find the values of the currents in the 3 Ohms resistance and the power there.

The equivalent resistance in section 1 would be

The equivalent resistance in section 2 would be

Now the total current will be,

Finally the total Voltage will be,

Since the voltage across the 3 and 6 Ohms resistor is the same, because they are in parallel, the current in section 3 would be

Finally the power ratio is the product between the current and the voltage then,

Therefore the correct answer is D.