To calculate the total output power, which two quantities are required?

To calculate the total output power, which two quantities are required?

• A. Output voltage and output amperes
• B. Output amperes and efficiency
• C. Input voltage and input amperes
• D. Output voltage and output resistance

Answer: (A)

The main concept is that total output power is found by multiplying the output voltage by the output current. This product, P = V × I, represents the rate at which the device delivers energy to the load, using the driving potential (voltage) and the amount of current it pushes (current). Efficiency is a separate idea that compares output power to input power, not a direct way to compute output power, so it’s not used to determine the value itself. Knowing the input voltage and input current tells you the input power, not the power delivered at the output. While you could also compute output power from voltage and resistance with P = V²/R, this requires knowledge of the load resistance and isn’t as direct as using the voltage and current the output actually provides. Therefore, the simplest and most direct way to calculate total output power uses the output voltage and the output current.

The main concept is that total output power is found by multiplying the output voltage by the output current. This product, P = V × I, represents the rate at which the device delivers energy to the load, using the driving potential (voltage) and the amount of current it pushes (current). Efficiency is a separate idea that compares output power to input power, not a direct way to compute output power, so it’s not used to determine the value itself. Knowing the input voltage and input current tells you the input power, not the power delivered at the output. While you could also compute output power from voltage and resistance with P = V²/R, this requires knowledge of the load resistance and isn’t as direct as using the voltage and current the output actually provides. Therefore, the simplest and most direct way to calculate total output power uses the output voltage and the output current.