Q. A student measures the terminal potential difference $(V)$ of a cell (of $emf\ E$ and internal resistance $r$) as a function of the current $(I)$ flowing through it. The slope, and intercept, of the graph between $V$ and $I,$ then, respectively, equal
A) $E$ and $–r$
B) $- r$ and $E$
C) $r$ and $–E$
D) $- E$ and $r$
Explanation
(b) $E = V + ir \Rightarrow V = - ri + E$
Comparing it with $y = mx + c;$ Slope $(m) = - r$ and intercept $= E$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.