Definition
A temperature-measuring instrument that works on the principle that the electrical resistance of a metal wire (typically nickel or platinum) changes in a known, predictable way as its temperature changes. The sensing element, called a bulb, is placed in the location whose temperature is to be measured, and a calibrated meter reads the resistance and displays the corresponding temperature.
Plain English
A thermometer that measures temperature by detecting how much harder it is for electricity to flow through a piece of wire. As the wire gets hotter, electricity has more difficulty passing through it, and the instrument converts that difficulty into a temperature reading on a gauge.
Context Anchor
Seen in aircraft temperature-indicating systems, such as systems that show oil temperature, air temperature, or other equipment temperatures.
Derivation
From the Latin resistere meaning 'to stand against.' Electrical resistance describes how much a material 'stands against' the flow of electricity. Since this opposition changes with temperature in a reliable way, it can be used to measure temperature accurately.
Why Pilots Care
Delivers accurate temperature data needed to monitor engine health and detect icing conditions.
Intuition Check
Do not read “resistance” here as general stubbornness or drag. In this term, resistance means opposition to electric current, and that opposition changes with temperature.
Example Sentence 1
The oil temperature gauge in the cockpit is driven by a resistance thermometer with its sensing bulb mounted in the engine's oil galley.
Example Sentence 2
The pilot checked the resistance thermometer reading before entering possible icing conditions.