Two cells of emf `E_(1) ` and `E_(2)` are to be compared in a potentiometer `(E_(1) gt E_(2))` . When the cells are used in series correctly , the balancing length obtained is 400 cm. When they are used in series but `E_(2)` is connected with reverse polarities, the balancing obtaiend is 200cm. Ratio of emf of cells is

Options

A. A) `3:2`
B. B) `3:1`
C. C) `4:1`
D. D) `4:3`

Answer

2

Explanation

Answer (2)
`E prop l `
`implies ( E_(1)+E_(2))/(E_(1)-E_(2))= (l_(1))/(l_(2))`