Equation 2 · Part 7 · The Last Artefact: Redefining the Kilogram

Symbol v

m_x g = I_1 B l \qquad\text{and}\qquad U_2 = v B l

v

What this part means

the velocity.

Its job in the formula

v is an input to the expression that computes the quantity on the left.

Full expressionSymbol vArticle meaning

Where the article explains it

In moving mode, the same coil is driven vertically at velocity v through the same field and the induced voltage U₂ is measured [ 4 ] : $m_x g = I_1 B l \qquad\text{and}\qquad U_2 = v B l$ .

The passage around this formula

The Kibble balance runs in two modes. In weighing mode, the weight of an artefact of mass m is balanced by the force on a coil of wire length l carrying current I₁ in a radial field of flux density B. In moving mode, the same coil is driven vertically at velocity v through the same field and the induced voltage U₂ is measured [ 4 ] : $m_x g = I_1 B l \qquad\text{and}\qquad U_2 = v B l$ . The geometric factor Bl appears in both and is eliminated between them:

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the surrounding passage

[4] Mise en pratique for the definition of the kilogram in the SI ↗

These citations provide research context; check each source for the exact claim it supports.