Figure shows a potentiometer circuit, a cell of emf `E_1` is balanced by length l' of the potentiometer wire. If this cell is replaced by another of emf `E_2`, it is found that total length of potentiometer wire has to be increased by 50%, in order to have the same balance length (l'). Then `E_1//E_2` is______.

Answer

A

Explanation

`E_1=E_A/l l'`
`E_2=E_A/((3l)/2)l'=2/3E_A/l l'=2/3E_1 rArr E_1/E_2=3/2`