Ohm

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Leeds and Northrup one ohm standard resistance

Electronic multi meter.jpg

Ohm
Unit system	SI derived unit
Unit of	Electrical resistance
Symbol	Ω
Named after	Georg Ohm
Conversions
1 Ω in ...	... is equal to ...
SI base units	1 Ω = 1 kg⋅m²⋅s⁻³⋅A⁻²

The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after Georg Ohm, a German physicist. It is defined as the resistance between two points of a conductor when a constant potential difference of one volt applied to these points produces a current of one ampere, meaning the conductor has no electromotive force.

Definition

The ohm is defined as the electrical resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces a current of one ampere. Mathematically, it is expressed as:

1 Ω = 1 V/A

History

The unit is named after Georg Simon Ohm, who first formulated Ohm's law. Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant. This relationship is often written as:

V = IR

where V is the voltage, I is the current, and R is the resistance.

Applications

Ohms are used in various applications to measure the resistance of electrical components and circuits. This measurement is crucial in designing and analyzing electrical and electronic systems, ensuring they operate efficiently and safely.

Related Units

• Milliohm (mΩ) - One thousandth of an ohm
• Kiloohm (kΩ) - One thousand ohms
• Megaohm (MΩ) - One million ohms

Measurement

Resistance is measured using instruments such as ohmmeters, which can be standalone devices or part of a multimeter. These instruments apply a known voltage to a resistor and measure the current flowing through it to determine the resistance.

See Also

• Ohm's law
• Electrical resistance
• Georg Ohm
• Volt
• Ampere
• Multimeter
• SI derived unit