Fig. illustrates a potentiometric circuit by means of which we can very a voltage `V` applied to a certain device possessing a resistance `R`. The potentiometer has a length `l` and a resistance `R_(0)` and voltage `V_(0)` is applied to its terminals. Find the voltage `V` fed to the device as a funciton of distanace `x`. Analyse separately the case `R gt gt R_(0)`.