In a meter bridge when the resistance in the left gap is `4 Omega` and an unknown resistance in the right gap the balance point is obtained at `40 cm` from the zero end. On shunting the unknown resistance with `4 Omega`, find the shift of the balance point on the bridge wire

Options

A. n series with 9 ` Omega`
B. Parallel to X `Omega`
C. In series with X `Omega`
D. Parallel to 9 ` Omega`

Answer

C

Explanation

The balanced condition of bridge is shown below in the first case

Then `, (X)/(9) = (40)/(60) rArr X = (2)/(3) xx 9 = 6 Omega`
To get the balance point at 50 cm from left end the balanced condition becomes,
`(X')/(9) = (50)/(50) = 1 rArr X = 9 Omega`
As, in series combination resistances are added, so to get `9Omega` at left gap the `3 Omega` resistance should be added in series with `X Omega (6+ 3 = 9 Omega)`