*Kirchhoff' Laws :**
First Law : The algebraic sum of current at a junction is zero, i.e., Σ I = 0. This implies that total current entering a junction is equal to total current leaving the junction.
Second Law : In a closed loop, the algebraic sum of the emfs is equal to the algebraic sum of the product of resistance and the respective current in them, i.e.
Σ E = Σ IR
Wheatstone Bridge : This is a circuit consisting of four resistances B Q, R and *, a galvanometer and a battery connected as follows :
The Wheatstone bridge is balanced when there is no current through the galvanometer. It means potential at B is equal to that at D. In such a case
P/Q = R/*
