Which equation expresses Ohm's Law?

Which equation expresses Ohm's Law?

• A. V = IR
• B. P = VI
• C. E = IR
• D. Q = V / I

Answer: (A)

Ohm's Law describes how voltage, current, and resistance relate in a conductor: the voltage across the component equals the current through it times its resistance. This is what V = IR expresses. It means the voltage is the product of how hard charges are pushed (current) and how much the component resists that flow (resistance). Knowing any two of the three lets you solve for the third—so if you know the current and resistance, you can find the voltage, or if you know the voltage and resistance, you can find the current, and so on. In practice, this relationship is what lets you see how changing one quantity affects the others. For instance, doubling the current through a fixed resistor doubles the voltage across it, and doubling the resistance with the same current doubles the voltage as well. The other expressions describe different ideas: P = VI gives power, not the basic current–voltage–resistance link; Q = V / I would mix charge with resistance and isn’t a valid form of Ohm's law; E = IR is essentially a variant form if you interpret E as the voltage across the element, but standard form for Ohm's law uses V = IR.

Ohm's Law describes how voltage, current, and resistance relate in a conductor: the voltage across the component equals the current through it times its resistance. This is what V = IR expresses. It means the voltage is the product of how hard charges are pushed (current) and how much the component resists that flow (resistance). Knowing any two of the three lets you solve for the third—so if you know the current and resistance, you can find the voltage, or if you know the voltage and resistance, you can find the current, and so on.

In practice, this relationship is what lets you see how changing one quantity affects the others. For instance, doubling the current through a fixed resistor doubles the voltage across it, and doubling the resistance with the same current doubles the voltage as well.

The other expressions describe different ideas: P = VI gives power, not the basic current–voltage–resistance link; Q = V / I would mix charge with resistance and isn’t a valid form of Ohm's law; E = IR is essentially a variant form if you interpret E as the voltage across the element, but standard form for Ohm's law uses V = IR.