A load requires 12 volts DC at 5 amperes. What is the minimum required power transformer rating?

Power in a DC circuit is calculated using Watt's Law, which states that Power (P) equals Voltage (E) multiplied by Current (I). The standard formula is P = E x I. For a load requiring 12 volts and 5 amperes, you simply multiply the two values: 12 V x 5 A = 60 watts. This is the absolute minimum power rating the transformer must have to supply the load without overloading. Incorrect answers are often the result of dividing the numbers (12 / 5 = 2.4) or simply adding them (12 + 5 = 17). Always remember to multiply voltage by current to find total watts.