A potentiometer wire of length 10 m is connected in series with a battery the emf of a cell balances against 250 cm length of wire if length of potentiometer wire is increased by 1 m then new balancing length of wire will be

Options

A. 2.00m
B. 2.25 m
C. 2.50 m
D. 2.75 m

Answer

D

Explanation

Balancing condition of potentiometer is given by
`(E_(1))/(E_(2))=(l_(1))/(l_(2))=(10xx100)/(250)=4 " " [because l_(1)=10 m` and `l_(2)cm]`
If `l_(2)` is increases by 1 m, then new length will be
`l'=10m+1 m=11m`
`therefore` New balancing length of wire `(l'_(2))` is
`(l'_(1))/(l'_(2))=(E_(1))/(E_(2)) rArr (11)/(l'_(2))=4 " " therefore " " l'_(2)=(11)/(4)=2.75 m`