
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
.