From fig(b), 4 ohms and 12 ohms are in parallel, equivalent is 3 ohms
From fig(c), 3 ohms and 3 ohms are in series, equivalent resistance is 6 ohms
From fig(d),
6 ohms and 6 ohms are in parallel, equivalent resistance is 3 ohms
From fig(e), 4 ohms, 3 ohms and 3 ohms are in series .Hence Req = 4+ 3+ 3 =10 ohms
Malla Reddy College of Engineering and Technology (MRCET)
Department of EEE ( 2017-18 )
Electrical Circuits EEE Series Connection of Inductors: Two or more inductors in a circuit are said to be in series when the current flowing through all
the inductors is the same.
Consider a series connection of
N inductors, as shown in Fig(a),with the equivalent circuit shown
in Fig(b). The inductors have the same current through them. Applying KVL to the loop,
V = V1 + V2 + ……+Vn = L1 . di/dt + L2 . di/dt + …… Ln . di/dt
= di/dt (L1 +L2+ … +Ln)
= di/dt(L eq)
where Leq is the equivalent Inductance of all the Inductances L1 ,L2 ,….and Ln in series.
Hence Leq of a series circuit consisting of n Inductances L1 ,L2, … Ln connected in series is
given by
Leq = L1 +L2+ … +Ln
Note: The equivalent Inductance Leq of a circuit with n Inductances L1, L2, ….Ln connected in
series is equal to the sum of the individual Inductances L1 ,L2, … Ln
Parallel Connection of Inductors: Two or more inductors in a circuit are said to be in Parallel when all the circuit inductors are connected to the same nodes and the same voltage is appearing across all these inductors Consider the circuit in fig(a) and using the Kirchhoff’s Current Law (KCL) at the node ‘a’ the
governing equation can be written as:
i = i1 + i2 + ……+in..........(1)
Malla Reddy College of Engineering and Technology (MRCET)
Department of EEE ( 2017-18 )
