While doing an experiment with potentiometer (figure) it was found that the deflection is one sided and (i) the deflection decreased while moving from one and A of the wire, to the end R, (ii) the deflection increased, while the jockey was moved towards the end D.
(i). Which terminal positive or negative of the cell `E_(1)` is connected at X in case (i) and how is `E_(1)`, related to E?
(ii). Which terminal of the cell `E_(1)` is connected at X in case (1 in 1)?

Explanation

In the given potentiometer experiment, the deflection in the galvanometer will be one sided if the emf of cell `E_(1)` is greater than the emf of battery `E` because than emf `E_(1)` is greater than fall of potential across the potentiometer wire due to battery `E`.
(a) The deflection in galvanometr will decrease while moving from one end `A` of the poteniomter wire to the end `B`, if positive of the cell `E_(1)` is is connected to `X` and negative of the cell to `Y`, because in this situation, the current in galvanometer decrease with the increase in length of potentiometer wire.
(b) The deflection in galvanometer will increase while moving from end `A` of the poteniomter wire to the end `B` if - ve of the cell `E_(1)` is connected to `X` and `+` ve to `Y`. In this situation, the current in galvanometer increases with the increase in the length of potentiometer wire.