Question

Gina examines the equations for electric power and Ohm's law. She thinks that there is a third equation that can calculate power using only voltage and resistance.

Which statement best evaluates Gina’s idea?

It is correct, because I = .
It is correct, because I = .
It is incorrect, because both equations for power use current.
It is incorrect, because Ohm’s law does not include I2.

Answer 1

Choose the statement that says Gina is correct because I = V/R.

Reason: Ohm’s law gives V = IR, so I = V/R. Substitute into P = I^2R (or into P = VI) to get P = (V/R)^2 R = V^2/R (or P = V(V/R) = V^2/R).