When a resistance is placed in parallel with a galvanometer on a circuit
the following relation obtains. Let s and g equal the resistances of the
shunt and galvanometer respectively, S and G the currents in amperes
passing through them, V the potential difference between their common
terminals, and A the whole current in amperes. Then we have
A = ( (s + g ) / s ) * G
and ( (s + g ) / s ) is termed the multiplying power of the shunt, as it
is the factor by which the current passing through the galvanometer must
be multiplied by to produce the total current.