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

Key Idea : This problem is based on the application of potentiometer in which we find the internal resistance of a cell. 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 = l₁ l₂ where l₁ 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 = l₁ l₂ aligned 1+ r R & = 110 100 r R & = 10 100 r & = 1 10 10=1 aligned r= 1 10 10