For a single-phase load with known power and power factor, which formula gives the current?

• A. I = P × PF / V
• B. I = P / (V × PF)
• C. I = V / (P × PF)
• D. I = V × PF / P

Answer: (B)

In a single-phase circuit, real power P comes from how much work is actually done, and it equals the product of voltage, current, and the power factor: P = V × I × PF. To solve for current, rearrange this relationship to I = P / (V × PF). This uses all three quantities correctly and shows why current increases if PF is lower (since you divide by PF, which is less than or equal to 1). If you instead multiply P by PF or place V in the numerator alone, you’d obtain currents that don’t satisfy P = VI × PF. For example, with P = 1000 W, V = 120 V, and PF = 0.8, the current should be about 10.4 A using the correct formula.