Under Ohm's law, if temperature remains constant, which relationship between current and voltage holds?

• A. Voltage is inversely proportional to current
• B. Current is directly proportional to voltage
• C. Resistance remains constant
• D. Power remains constant irrespective of voltage

Answer: (B)

Current is directly proportional to voltage when temperature is held steady and the material follows Ohm’s law. Ohm’s law says V = IR, so solving for current gives I = V/R. If the temperature doesn’t change, the resistance R stays the same, so increasing voltage makes the current increase by the same factor. For example, with a constant resistance, doubling the voltage doubles the current.

This isn’t an inverse relationship, which would imply current and voltage move in opposite directions. The statement that resistance stays constant is a condition that allows the direct relationship, and the idea that power stays constant is incorrect because power changes with voltage (P = VI or P = I^2R).