State Kirchhoff's law for an electrical network. Using these laws deduce the conditions for balance in a wheatstone bridge.

Explanation

1. Juntion Law : At any junction point in a circuit where the current can divede, the sum of the currents into the junction must equal From the figure, we have
`I_(1)+I_(4)+I_(6)+=I_(5)+I_(2)+I_(3)`
This law is based on the conservation of charge.

2. Loop law : The algebrate sum of the increases and decreases in potential difference across various components of the circuit in a closed circuit loop must be zero. This law is based on the conservation of the energy.
Ex : Let us imagine in a circuit loop the potential difference between the two points at the begining of the loop has a certain value. As we move around the circuit loop and measure the potential difference across each component in the loop, the potential difference may decrease or increase or increase depending upon the nature of the element like a resistor or a battery. but when we have completely traversed the circuit loop and arrive back at our starting point , the net change in the potential differece must be zero.