Which resistor consumes the largest energy? Use Power equation : V2/R It is easy and faster to see which is largest power, ie R1 as the pd is the greatest at 12 V . The formula also squares the voltage , thus it is a greater factor. The other three resistors are in series. The current flowing through the three resistors are the same. Hence using P = I2R , the resistor with the largest resistor has the greatest power among the 3 in series. Compare this value with the resistor in parallel to determine the greatest power of all four resistors.