Question

The y-intercept of the graph between the terminal voltage \(V\) with load resistance \(R\) along \(y\) and \(x\) – axis, respectively, of a cell with internal resistance \(r\), as shown, is: 

• A. \(\varepsilon\)
• B. \(-\varepsilon\)
• C. \(\frac{\varepsilon}{R}\)
• D. \(\varepsilon R\)
• E. \(-\varepsilon R\)

Hint:

In an open circuit condition, the terminal voltage of a battery equals its electromotive force (\(\varepsilon\)).

Answer 1

The Correct Option is A

The terminal voltage \(V\) of a cell can be expressed by the equation: \[ V = \varepsilon - Ir \] where \(I\) is the current through the cell. When \(R \rightarrow \infty\) (open circuit condition), \(I = 0\), and thus \(V = \varepsilon\). 
Therefore, the y-intercept of the graph is the emf of the cell, \(\varepsilon\).