A cell in secondary circuit gives null deflection for 2.5m length of potentiometer having 10m length of wire. If the length of the potentiometer wire is increased by 1 m without changing the cell in the primary, the position of the null point now is :

Options

A. 3.5 m
B. 3 m
C. 2.75 m
D. 2.0m.

Answer

C

Explanation

`Lpropl`
`(L_(1))/(L_(2))=(l_(1))/(l_(2))`
`10/11=(2.5)/(l_(2))`
`10l_(2)=2.5xx11`
`l_(2)=(2.5xx11)/10=2.75m`