A potentiometer wire AB having length L and resistance 12 r is joined to a cell D of emf `epsi//2` and internal resistance 3r is connected. The length AJ at which the galvanometer as shown in fig. Shows no deflection is :

Options

A. `13/24 L`
B. `11/12 L`
C. `11/24 L`
D. `5/12 L`

Explanation

`i=E/(13r) , E/2=e-jR_x`
`=E-e/(13r) times (x/L times 12r),1/2=12/13 x/L implies x=13/24 L`