Which formula expresses electrical power in terms of current and resistance?

Which formula expresses electrical power in terms of current and resistance?

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

Answer: (C)

Power dissipated in a conductor is determined by how much current flows through it and its resistance, and the form P = I^2 R expresses that relationship directly. Start from the basic power formula P = VI. Using Ohm’s law V = IR, substitute into P = VI to get P = I (IR) = I^2 R. This shows power depends on the square of the current and linearly on the resistance, so doubling the current makes the power four times larger, while doubling the resistance doubles the power for a given current. Forms that include voltage, like P = V^2 / R or P = VI, involve voltage rather than expressing power with only current and resistance, and P = V/I doesn’t represent power at all.

Power dissipated in a conductor is determined by how much current flows through it and its resistance, and the form P = I^2 R expresses that relationship directly. Start from the basic power formula P = VI. Using Ohm’s law V = IR, substitute into P = VI to get P = I (IR) = I^2 R. This shows power depends on the square of the current and linearly on the resistance, so doubling the current makes the power four times larger, while doubling the resistance doubles the power for a given current. Forms that include voltage, like P = V^2 / R or P = VI, involve voltage rather than expressing power with only current and resistance, and P = V/I doesn’t represent power at all.