^Circuit to find ‘r’ of a cell
Circuit to find ‘r’ of a cell
When the switch S is closed & the switch S1 is kept open, then the cell of emf ξ is said to be in open circuit. Let here the balancing length is b1, then ξ ∝ b1 Now when the switches S & S1 are closed, then the cell of emf ξ is said to be in closed circuit.
Let here the balancing length is b2, then V ∝ b2
Dividing above two relations we get 
