Two equal resistances are introduced in two gaps of a metre bridge. The shift in the null point if an equal resistance is connected in series with resistance in left gap is

Options

A. 16.6 cm
B. 16.6m
C. 16.6mm
D. 66.6 cm

Answer

A

Explanation

(i) `(X)/(R)=(l_(x))/(l_(R)):.L_(x)=l_(R)=50cm( :'x=R)`
(ii) Now, if `X=2R`
`(2R)/(R)=(l_(x))/(100-l_(x)) 200 -2l_(x)=l_(x)`
`:.l_(x)=66.6 cm`
(iii) Shift `=66.66-50=16.66cm`