Final answer:
Gina is correct; an equation for electric power that uses only voltage and resistance is P = V²/R, derived from Ohm's law (V = IR) and the power equation (P = IV).
Step-by-step explanation:
Gina's idea that there is a third equation to calculate electric power using only voltage and resistance is correct. This is because by combining Ohm's law (V = IR) with the power equation (P = IV), we can eliminate the current (I) and derive new expressions for power. We obtain P = V²/R, which uses only voltage (V) and resistance (R), as well as P = I²R, which uses only the current (I) and resistance (R).
Ohm's law also helps us to transform the relationship between current, voltage, and resistance in different ways. For example, if you have voltage (V) and resistance (R), you can use the equivalent expression for electric power P = V²/R to calculate the power without knowing the current.
Therefore, the statement that best evaluates Gina's idea is A) It is correct, because I = V/R, which when substituted into P = IV, gives the equation for power as P = V²/R, an expression that includes only voltage and resistance.