SI units

SI units problem 21

  • The current in a wire is . Charge passes one point in the wire in time . State

    • the relation between , and ,

    • which of the quantities , and are base quantities.

  • The current in the wire is due to electrons, each with charge , that move with speed along the wire. There are of these electrons per unit volume.

    For a wire having a cross-sectional area , the current is given by the equation:

    where is a constant.

    • State the units of , , , and in terms of the base units.

    • By considering the homogeneity of the equation, determine the value of .


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