A cell can be balanced against 110 ~cm and 100 ~cm of potentiometer wire, respectively with and without being short circuited through a resistance of 10 . Its internal resistance is

Step-by-step solution

In potentiometer experiment in which we find internal resistance of a cell, let E be the emf of the cell and V the terminal potential difference, then E V = h l₂ where l and l₂ are lengths of potentiometer wire with and without short circuited through a resistance. Since, E V = R+r R [ E=I(R+r) and V=I R] R+r R = 4 l₂ or 1+ r R = 110 100 Or r R = 10 100 or r= 1 10 10=1