Definition
The unit of electrical resistance. One ohm is the resistance that allows one ampere of current to flow when one volt is applied across it. The symbol for ohm is the Greek letter omega (Ω).
Plain English
A measurement of how much a material pushes back against electricity trying to flow through it. More ohms means less current gets through for the same voltage.
Context Anchor
Seen in aircraft electrical system checks, wiring tests, component specifications, and maintenance manual limits.
Derivation
Named after Georg Simon Ohm, a German physicist who in 1827 described the relationship between voltage, current, and resistance — now known as Ohm's Law. The unit was named in his honor.
Why Pilots Care
Correct resistance values ensure reliable operation of electrical systems, prevent overheating, and allow accurate troubleshooting of faults.
Analogy
Think of a garden hose. Voltage is the water pressure, current is the water flowing, and ohms are how narrow or kinked the hose is. More kinks (more ohms) means less water flows for the same pressure.
Intuition Check
An ohm is not a measure of how much electricity is available. It is a measure of how strongly something resists electric current.
Example Sentence 1
The technician measured 0.2 ohms across the bonding strap, confirming a good electrical connection to the airframe.
Example Sentence 2
An open wire produced an infinite ohm reading on the multimeter, indicating a break that needed repair.