Which expression represents power using current and resistance in a DC circuit?

Which expression represents power using current and resistance in a DC circuit?

• A. P = V × I
• B. P = V ÷ R
• C. P = I² × R
• D. P = I × R

Answer: (C)

Power dissipated by a resistor in a DC circuit can be expressed using current and resistance as P = I^2 R. This comes from Ohm’s law V = IR and the power relation P = VI. Substituting V with IR gives P = I(IR) = I^2 R. This form shows how power grows with the square of the current and is proportional to the resistance for a given current. For intuition, doubling the current makes power four times larger, and higher resistance at the same current increases power linearly. Other expressions involve voltage (P = VI) or don’t directly express power in terms of current and resistance (P = V/R or P = IR, where IR is voltage, not power).

Power dissipated by a resistor in a DC circuit can be expressed using current and resistance as P = I^2 R. This comes from Ohm’s law V = IR and the power relation P = VI. Substituting V with IR gives P = I(IR) = I^2 R. This form shows how power grows with the square of the current and is proportional to the resistance for a given current. For intuition, doubling the current makes power four times larger, and higher resistance at the same current increases power linearly. Other expressions involve voltage (P = VI) or don’t directly express power in terms of current and resistance (P = V/R or P = IR, where IR is voltage, not power).