To study complicated circuits containing more than one source of emf, Kirchhoff put forward
the following two laws in
1842.
Before going to the Kirchhoff’s laws, let us first define two terms. A
node in a network is a
point where three or more conductors are joined. A
loop is any closed conducting path.
(i) First Law or Current Law
It states, “In any electrical network, the
algebraic sum of currents meeting at a point (or junction) is zero, .”
The total current flowing towards a node (junction) is equal to the total current flowing away from that node,
i.e. the algebraic sum of the currents meeting at a node is zero. The first law is simply a statement
of the
conservation of charge .
(ii) Second law or Mesh law or Voltage law
It states, “In a closed circuit, the
algebraic sum of the products of the current
and the
resistance in each of the conductors in any closed path (or mesh) in a network
plus
sum of emfs in that path is equal to zero.”
