When resistances R_{1}, R_{2}, R_{3}, ... are connected in parallel, the total resistance R_{P} is:
1 / R_{P} = 1 / R_{1} + 1 / R_{2} + 1 / R_{3} + ...
Alternatively, when conductances G_{1}, G_{2}, G_{3}, ... are connected in parallel, the total conductance G_{P} is:
G_{P} = G_{1} + G_{2} + G_{3} + ...
where G_{n} = 1 / R_{n}
For two resistances R_{1} and R_{2} connected in parallel, the total resistance R_{P} is:
R_{P} = R_{1}R_{2} / (R_{1} + R_{2})
R_{P} = product / sum
The resistance R_{2} to be connected in parallel with resistance R_{1} to give a total resistance R_{P} is:
R_{2} = R_{1}R_{P} / (R_{1} - R_{P})
R_{2} = product / difference |