What is the relationship between voltage, current, and resistance in a practical circuit with a fixed supply?

What is the relationship between voltage, current, and resistance in a practical circuit with a fixed supply?

• A. V = IR; I = V/R; R = V/I
• B. V = I^2 R
• C. R = VI
• D. I = R/V

Answer: (A)

In a circuit with a fixed supply, the relationship between voltage, current, and resistance is governed by Ohm’s law: V = IR. Since the supply voltage V is constant, the current is determined by the resistance as I = V/R, and the resistance can be found as R = V/I. This means current moves inversely with resistance: increasing resistance lowers the current, and decreasing resistance raises the current, while the supply voltage stays the same. The other options aren’t correct because they mix the quantities in ways that aren’t consistent with V = IR. V = I^2R is not a general expression for voltage (it mixes current and resistance in a way that describes power, P = I^2R, or V^2/R for power), while R = VI and I = R/V do not follow from Ohm’s law. The valid relationships are the connected forms of V = IR: V = IR, I = V/R, and R = V/I.

In a circuit with a fixed supply, the relationship between voltage, current, and resistance is governed by Ohm’s law: V = IR. Since the supply voltage V is constant, the current is determined by the resistance as I = V/R, and the resistance can be found as R = V/I. This means current moves inversely with resistance: increasing resistance lowers the current, and decreasing resistance raises the current, while the supply voltage stays the same.

The other options aren’t correct because they mix the quantities in ways that aren’t consistent with V = IR. V = I^2R is not a general expression for voltage (it mixes current and resistance in a way that describes power, P = I^2R, or V^2/R for power), while R = VI and I = R/V do not follow from Ohm’s law. The valid relationships are the connected forms of V = IR: V = IR, I = V/R, and R = V/I.