Ohm

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 the German physicist Georg Ohm. 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 a resistance of one ohm.

Definition

The ohm is defined by Ohm's law, which states that the resistance (R) in ohms is equal to the potential difference (V) in volts divided by the current (I) in amperes: \[ R = \frac{V}{I} \]

History

The unit is named after Georg Simon Ohm, who first formulated Ohm's law. His work was published in 1827 in the book "Die galvanische Kette, mathematisch bearbeitet" (The Galvanic Circuit Investigated Mathematically).

Practical Applications

Ohms are used in various practical applications, including:

• Electrical engineering
• Electronics
• Physics
• Telecommunications

Measurement

Electrical resistance is measured using an instrument called an ohmmeter. Modern digital multimeters can measure resistance, voltage, and current.

Related Units

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

See Also

• Ohm's law
• Electrical resistance
• Georg Ohm
• Volt
• Ampere
• Siemens (unit)