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KINETIC ENERGY OF ELECTRICITY IN MOTION [1]
electricities, i.e. the total kinetic energy of the current in a
cubic millimetre of a conductor in which the current has unit
magnetic density.
The object of the following experiments is to determine
the quantity, or at any rate an upper limit to it.
METHOD OF EXPERIMENTING.
Since we have put the kinetic energy of the total electricity
equal to mi²/2, and also equal to (lµ/q)², it follows that
μ=qm/21. In order to determine m it would have sufficed
to measure the integral flow of the extra-current in a con-
ductor of known resistance r and self-inductance P; m would
at once follow from the equation J = (i/r)(P+m). But
extra-currents can only be measured in branched systems of
conductors, and this would necessitate the measuring of a
large number of resistances. Hence it is preferable to
generate extra-currents in the same circuit by two different
inductions, when we obtain two equations for the quantities
r and m. If the current in the unbranched circuit is to that
current by which the extra-current is measured as a : 1, and
if J is the total flow measured, then the equations in
question are
whence
arJ
arJ'
and = P+m, a' = P'+m,
m =
ï
pl - pr
i
Ꭻ
J'
i i
It is well to choose one inductance P' so large that the
influence of mass is negligible in comparison, but the other P
as small as possible. The equations then take the simpler
form
arJ = P+m,
arJ'
¿ =
·P':
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