Which expression gives electrical power in terms of current and resistance?

Which expression gives electrical power in terms of current and resistance?

• A. P = V × I
• B. P = V^2 / R
• C. P = I^2 × R
• D. P = V × R

Answer: (C)

Power is the rate at which energy is converted in a circuit. When current flows through a resistor, the voltage across that resistor is V = IR. The power delivered to the resistor is P = V × I. Substituting V with IR gives P = I × (IR) = I^2 × R, which uses only current and resistance. This matches the requirement to express power in terms of current and resistance. The other common forms, like P = V × I or P = V^2 / R, involve voltage and aren’t written solely with current and resistance. An incorrect-looking form like P = V × R doesn’t yield correct power units, so it’s not valid.

Power is the rate at which energy is converted in a circuit. When current flows through a resistor, the voltage across that resistor is V = IR. The power delivered to the resistor is P = V × I. Substituting V with IR gives P = I × (IR) = I^2 × R, which uses only current and resistance. This matches the requirement to express power in terms of current and resistance. The other common forms, like P = V × I or P = V^2 / R, involve voltage and aren’t written solely with current and resistance. An incorrect-looking form like P = V × R doesn’t yield correct power units, so it’s not valid.