In a metre bridge , the gaps are enclosed by resistances of `2omega` and `3Omega` . The value of shunt to be added to `3Omega` resister to shift the balancing point by 22.5cm is

Options

A. `1Omega`
B. `2Omega`
C. `2.5Omega`
D. `5Omega`

Answer

A

Explanation

`R= (pl)/(A)'R_1= (P_1X_1)/(A), R_2 = (P_2X_2)/(A)`
Equivalent resistance in series , `R= R_1+R_2`
`(p(X_1+X_2))/(A) = (P_1X_1)/(A)+(P_2X_2)/(A)`
therefore p= `(P_1X_1+P_2X_2)/(X_1_X_2)`