
31
law. Calling the currents respectively I
x
and 7
2
, we therefore know
that /j = E/R
ι
and I
2
= E/R
2
. The total current drawn is the sum of
the two: it is
In the equivalent circuit of Fig. 2.10Z? the current is E/R, which
may also be written Ε (\/R). Since, for equivalence between the
circuits, the current must be the same for the same battery voltage,
we see that
R "
+
R
2
Generalising from this result, we conclude that: The reciprocal of
the equivalent resistance of several resistances in parallel is equal to
the sum of the reciprocals of their individual resistances. It follows
from this that the effective resistance of a number of resistance ...