3. INTRODUCTION
Kirchhoff’s laws is used for calculation of the
currents, voltages and resistances of electrical
networks.
Kirchhoff’s law is two types:-
1.Kirchhoff’s current law
2.Kirchhoff's voltage law
Presentation title 3
4. KIRCHHOFF’S LAWS
Kirchhoff’s current law:-
It states that in a given instant the algebraic sum of all the current at
a given node or junction in a network is zero.
Kirchhoff's voltage law:-
It states that the algebraic sum of voltages around a closed path of
any electrical network at a given instant is zero.
5. KIRCHHOFF’S CURRENT LAW:-
At any junction in a circuit, the current that enters the junction
equals the current that leaves the junction.
EXAMPLE:-
At the junction
shown: I1+I2=I3
Kirchhoff's voltage law:-
Going around any complete loop in a circuit,
the sum total of all the potential difference is
zero.
EXAMPLE:-
Going around the right loop:
V1-I1R1-V2+I2R2=0
7. EXAMPLE 2
Applying KVL in loop 1
10 - 3i1 - 5 (i1-i2) =0
-8i1 + 5i2 = -10
Applying KVL in Loop 2
-3i2 - 1i2- 5 (i2-i1) = 0
5i1 - 9i2 = 0
Substituting and solving both equations we will
get
-40i1 -25i2 = -50
72i2 +40-i1 = 0
-97i2 =-50
So, i2 = 0.515 A
After substituting I2 to equation we got I1 current
i1 = 1.571 A