What measurement changes when an electric current passes through a resistor?

When an electric current passes through a resistor, the measurement that typically changes is voltage. According to Ohm's Law, the relationship between voltage (V), current (I), and resistance (R) is described by the equation V = I × R. When a current flows through a resistor, the voltage drop across the resistor is dependent on the amount of current flowing and the resistance of the material.

If the current increases or decreases, the voltage across the resistor will also adjust accordingly, reflecting the changes in current while maintaining a constant resistance (assuming the resistor's temperature remains stable and its material properties are unchanged).

In this context, while resistance remains constant for an ideal resistor, the current and voltage can vary. Power, defined as the product of voltage and current (P = V × I), will also be influenced since it is derived from these two changing parameters. However, the most direct measurement that changes in relation to the flow of current through a resistor is the voltage.