Definition 1 of 2
Definition
An electrical component whose resistance can be adjusted across a range of values, used to control the amount of current flowing in a circuit or the voltage applied to part of a circuit. Common forms include the rheostat (two terminals, used to control current) and the potentiometer (three terminals, used to divide voltage).
Plain English
A resistor with a knob or slider that lets you change how much it resists the flow of electricity. Turning it one way lets more current through; turning it the other way restricts the current.
Context Anchor
Seen in aircraft electrical system discussions, maintenance troubleshooting, lighting controls, and other adjustable electrical controls.
Derivation
Variable comes from the Latin variare, meaning to change. Resistor comes from the Latin resistere, to hold back or oppose. So a variable resistor is literally a component that holds back electrical current by an amount you can change.
Why Pilots Care
Variable resistors are the components behind common cockpit adjustments such as panel light dimmers and certain instrument controls. Knowing how they work helps a technician troubleshoot dim, flickering, or unresponsive controls.
Analogy
Think of a kitchen tap. A fixed resistor is like a tap stuck at one setting. A variable resistor is a tap you can turn to let more or less water through.
Intuition Check
Do not assume “variable” means the resistor changes by itself. In this term, it means the resistance is adjustable by a control, movement, or circuit design.
Example Sentence 1
The pilot turned the variable resistor on the panel light dimmer to reduce cockpit glare during the night flight.
Example Sentence 2
During troubleshooting, the mechanic checked the variable resistor in the fuel quantity circuit for smooth operation.