Given charge q, current I and permeability of vacuum μ₀, which of the following quantities has the dimension of momentum?
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Question

Given charge q, current I and permeability of vacuum μ₀, which of the following quantities has the dimension of momentum?

G1 Physics · Accepted Answer

For a long straight current-carrying conductor, the magnetic field has the dimensional form B ∝ μ₀I/L. Therefore, μ₀I ∝ BL. For a charged particle moving in a magnetic field, qvB has the dimension of force, so qBL has the dimension of momentum because p = qBr for circular magnetic motion. Thus qμ₀I has the same dimensions as qBL, i.e. momentum. Correct option: A.