In a wheat stone bridge experiment to determine the unknown resistance `R_(4)`, the values of `R_(1) and R_(2)` were taken to be `10 Omega and 1 Omega` respectively. It was found that the galvanometer will show exact zero deflection when value of `R_(3)` is taken as `643 Omega lt R_(3) lt 644 Omega`.
Now `R_(1)` is changed to `100 Omega` (`R_(2)` remains unchanged).
(a) If you have been asked to obtain a balanced bridge, which values of `R_(3)` will you try with?
(b) If balance is obtained for `6432 Omega lt R_(3) klt 6433 Omega` write the measured value of unknown resistance `R_(4)`.

Answer

(a) We should try with `6430 Omega lt R_(3) lt 6440 Omega`
(b) `R_(4) = 64.325 Omega`