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Equation 2 · Part 9 · The Last Artefact: Redefining the Kilogram

subscript

mxg=I1BlandU2=vBlm_x g = I_1 B l \qquad\text{and}\qquad U_2 = v B l
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

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 ] : mxg=I1BlandU2=vBlm_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 subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the surrounding passage

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