To compute current from the given relationships, which two quantities are needed?

• A. Power and resistance
• B. Power and voltage
• C. Voltage and resistance
• D. Current and voltage

Answer: (B)

Current can be found directly from the relationship that power equals voltage times current. If you know how much power is being used and the voltage across the device, you can solve for current by dividing power by voltage. In formula form, I = P / V. This two-quantity pair lets you get current immediately without needing any other values. For example, if a device uses 120 watts at 12 volts, the current is 120 / 12 = 10 amps. Other pairs like voltage and resistance can also yield current, but they require a different formula (I = V / R), so the most direct two-quantity combination from the common power relation is power and voltage.