In order ot determine the e.m.f. of a storage battery is was connected in series with a stantard cell (both are adding) in a certain circuit and a current `I_(1)` was obtained. When polarity of the stantdard cell is reversed, a current `I_(2)` was obtained in the same direction as that of `I_(1)`. What is the em.f. `epsilon_(1)` of the storage battery? The e.m.f. of the stantard cell is `epsilon_(2)`.

Options

A. `epsilon_(1) = (I_(1) + I_(2))/(I_(1) - I_(2)) epsilon_(2)`
B. `epsilon_(1) = (I_(1) + I_(2))/(I_(2) - I_(1)) epsilon_(2)`
C. `epsilon_(1) = (I_(1) - I_(2))/(I_(1) + I_(2)) epsilon_(2)`
D. `epsilon_(1) = (I_(2) - I_(1))/(I_(1) + I_(2)) epsilon_(2)`

Answer

A

Explanation

(a) `epsilon_(1) + epsilon_(2) = I_(1) R, epsilon_(1) - epsilon_(2) = I_(2) R`
Dividing `epsilon_(1) = ((I_(1) + I_(2))/(I_(1) - I_(2))) epsilon_(2)`