IGCSE Physics Electricity Practice Test 2026 – Your Complete All-in-One Guide to Exam Success!

Being able to adjust resistance means the device lets you change how much of the resistive material the current travels through. For a uniform resistor, the resistance is proportional to the length of the path the current takes. So by moving a contact along the resistor to pick a different portion of the track, you change the length the current flows through and thus change the resistance. This is the hallmark of a variable resistor.

A potentiometer is a specific type of variable resistor with a sliding contact, and it’s often used as a voltage divider. When used as a two-terminal component, it also behaves as a variable resistor, but its main common use is as a three-terminal device for dividing voltage. The other options describe resistors whose resistance is fixed and does not change.