D – 48 watts
Units are very important in solving this question!
Here is a quick review:
Current is measured in amps.
Resistance is measured in ohms
Power is measured in watts
Voltage is measured in volts
There are two formulas necessary to solve this:
Power = voltage x current (or P = V x I )
Current = voltage / resistance (or I = V/R)
We are only given voltage and resistance in the question. So we will start by solving for the current in amps.
Current = 12 v / 3 Ω = 4 amps
Next we take the current we just solved for and use it in the formula to solve for power.
Power = 12 v x 4 amps = 48 watts
So the Power is 48 watts.