If you consider a connection of a set of series resistors connected in a parallel circuit, you get a parallel-series circuit. Let R1 and R2 be connected in series to give an effective resistance of Rs1 . Similarly, let R3 and R4 be connected in series to give an effective resistance of Rs2 .
Then, both of these serial segments are connected in parallel.
Parallel - series combination of resistors
Using equation
Rs = R1 + R2 + R3
We get
Rs1 = R1 + R2 , Rs2 = R3 + R4
Finally, using equation
\(\frac{1}{R_P} = \frac{1}{R_1} + \frac{1}{R_2}+ \frac{1}{R_3}\)
the net effective resistance is given by
\(\frac{1}{R_total} = \frac{1}{R_{s1}} + \frac{1}{R_{s2}}\)
