mho

mho — noun

1. A scientific unit used for measuring how easily an electric current can pass thr

1.nounC2
Definition

A scientific unit used for measuring how easily an electric current can pass through a material or component. One mho is the equivalent of one siemens, the modern standard term, and is found by dividing 1 by the resistance measured in ohms.

Example

To find the mho value of the copper wire, divide one by the resistance in ohms.

reciprocal of ohms: mho = 1 ÷ ohm

Two mhos of conductance means current flows twice as easily as through a 1-ohm resistor.

Common collocations
  • one mho
  • mhos of conductance
  • measured in mhos
  • mho value
Synonyms
  • siemens

    The modern SI name for the same unit; siemens is the preferred term in current scientific writing, while mho is historical or niche.

Antonyms
  • ohm

    The unit of electrical resistance; ohm and mho are mathematical reciprocals of each other (1 mho = 1 / 1 ohm).

Usage Note

The word mho is ohm spelled backwards, and its symbol ℧ is an upside-down capital omega. The term has largely been replaced by siemens (symbol S) in modern SI use, but it still appears in older technical texts and some engineering contexts.

Common Mistakes

The mho measures resistance in a circuit.
The mho measures conductance in a circuit.
Mho is the opposite of ohm: it measures how easily current flows, not how much it resists.
The wire has 5 mhos of resistance.
The wire has 5 mhos of conductance.
Conductance and resistance are different properties; mho always describes conductance.

Synonym discussion

Sense: noun/1

Mho and siemens are two names for the same unit of electrical conductance — they are exact equivalents (1 mho = 1 S). The difference is purely historical and stylistic: mho (ohm spelled backwards) dates from the late 19th century and appears mainly in older textbooks, while siemens is the official SI name used in modern physics and engineering. Ohm, by contrast, measures resistance, the inverse property. Where a material has 10 ohms of resistance, its conductance is 0.1 mho (or 0.1 S). For everyday usage in a technical report, choose siemens for formal scientific writing; use mho only when quoting historical sources or referring to older equipment specifications.

mho ↗siemens ↗ohm

Common collocations

Nouns

Phrases

  • reciprocal of ohm

Prepositions

  • in mhos
  • of mho

Etymology

English (reverse spelling of 'ohm')German (Georg Ohm, namesake of the ohm)

The word 'mho' was created in the late 1800s by writing 'ohm' backwards. At that time, scientists working with the newly discovered laws of electricity needed a name for the unit that was the mathematical opposite of the ohm. The symbol ℧ mirrors this idea — it is an upside-down capital omega (Ω), the symbol for ohm. Although the International System of Units later adopted 'siemens' as the official name, 'mho' remains in use in some technical fields and historical references.