Definition
In an electrical circuit, the opposition a material offers to the flow of electric current. Resistance is measured in ohms (Ω) and converts electrical energy into heat as current passes through. It is one of the three fundamental quantities in Ohm's Law, where voltage equals current multiplied by resistance (E = I × R).
Plain English
How much a material pushes back against electricity trying to flow through it. The higher the resistance, the harder it is for current to get through, and the more heat is produced along the way.
Context Anchor
Seen in aircraft electrical system discussions, troubleshooting, wiring checks, and component testing with a meter.
Derivation
From the Latin 'resistere,' meaning 'to stand back' or 'to oppose.' That original sense fits perfectly here -- resistance is the material 'standing against' the flow of current.
Why Pilots Care
High resistance creates heat, reduces voltage, and can cause electrical failures or fires in critical aircraft systems.
Analogy
Think of water flowing through a hose. A wide, smooth hose lets water flow easily (low resistance). A narrow, kinked hose slows the flow and warms up where it pinches (high resistance). Electricity behaves the same way through a wire or component.
Intuition Check
Resistance does not just mean refusing or pushing back in a general sense. In aircraft electrical work, it means opposition to the flow of electric current, measured in ohms.
Example Sentence 1
The technician measured the resistance across the landing light filament with a multimeter to confirm the bulb wasn't burned out.
Example Sentence 2
Corrosion increased the resistance at the battery terminal and prevented the starter from engaging.