In an experiment with a potentiometer, it was found that no deflection is caused in the ammeter on joining the two terminals with cells with 125 cm length of the potentiometer wire. If the resistance of 2Ω s connected to the terminal of the cell, then the balancing length is 100 cm, calculate the internal resistance of cell:
1
0.5 Ω
2
1.5 Ω
3
1.25 Ω
4
4/5 Ω