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308 Molesworth’s pocket-book
Electromagnets—continued.
With relation to the battery :•—
Let the accentuated quantities represent the
values from a typical electromagnet; then
ne \/ n p + r .
n' e' n' p + r'
= (-0225 v///r>2Y= M; and
n p 4- \ '
„ = ^ + v7“5y+^.
If i represent the number of series and h the
number of each member of the series in parallel
i
arc, the internal resistance becomes — • p and
i h = ■— . M. Under these conditions,
e2
x 0-173.
V p
Derivations.
If x be the number of derivations from the
same pole of the battery, the value of h i or of n
will be the same as in the simple case, but multi-
plied by x.
For circuits of equal resistances the diameter
of the electromagnet should be proportional to
tli© e. m. f.
For equal e. m. f. the diameter varied ab
J total res.
For equal diameter, E a a/ res.
For given electromagnetic force, E a < rea.