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Asked in GUJCET 2025 · Units and dimensions
Given: the current sensitivity of a moving-coil galvanometer.
Idea: current sensitivity is the deflection produced per unit current, θ/I.
A deflection is an angle in radian -- a pure number -- so [θ/I]=1/(A¹)=[A⁻¹].
Check it through the instrument's own relation. At balance the deflecting couple equals the restoring couple, NIAB=kθ, so θ/I=(NAB)/k.
[NAB]=L²×M¹L⁰T⁻²A⁻¹=M¹L²T⁻²A⁻¹ and [k]=M¹L²T⁻², so the ratio is A⁻¹ -- the same.
So the current sensitivity has the dimensions [A⁻¹], and is quoted in divisions per ampere.
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