Question

principle of potentiometer

Answer 1

PRINCIPLE OF POTENTIOMETER :::::::::::Potentiometer is a simple device used to measure the EMF, TPD, internal resistance of a cell. It consists of a board where a tungsten or manganese wire is fitted on it. It works on the principle that the potential dropped between two points in a wire of uniform cross section is directly proportional to the distance between the points.

Driving cell (E) of some EMF which is always greater than the EMF (E’) to be measured is used to send current through the circuit. It drops uniform potential along the potentiometer wire AB.

Between A and X (some point in between A and B), some potential (say V) is dropped. Consider the alternative path wire AGX for the flow of current in between A and X except the potentiometer wire. The potential due to driving cell is same for both AX segment of wire and the long wire AGX since they are in parallel. Thus, electric field exists along AGX. When a cell E’ is introduced with positive connected to A in the path AGX, it creates opposite field to that created by the driving cell, and thus when V = E’, no current flows through the portion AGX which is confirmed by the galvanometer (G). Thus, we get E’ ∝d

Answer 2

principal of operation. poteniometer is a simple device used to measure EMF, TPD, internal resistance of cell. It consist of boaredd where tungsten and manganese wire fitted on it. It drops uniform potential along the potentiometer wire.