In various electrical appliances, resistors are often used in combinations. Usually, they are connected either in series or in parallel.
V=V1+V2+V3 eq. 1
According to Ohm's law,
Vr=IRs(where
Rs is the effective resistance in series combination)
V1=IR1V2=IR2V3=IR3Substituting these values in equations 1,
IRs=IR1+IR2+IR3IRs=I(R1+R2+R3)Striking off '
I' from the both sides of the equation,
Rs=R1+R2+R3Thus, the
effective resistance of a series combination of resistance is the sum of individual resistances of the resistors in the combination.
Characteristics of the series combination of resistors are:
(a) The value of the current
′I′ flowing through the resistors connected in series is the
same through each resistor.
(b). The potential difference
′V′ across the resistors connected in series is equal to the sum of individual potential differences across each resistor.