Q. A student measures the terminal potential difference (V) of a cell (of emf ε 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) −r and ε
B) r and −ε
C) −ε and r
D) ε and −r
Explanation
[Solution from source] Terminal voltage V = ε − Ir, a straight line in I. Its slope is −r and its intercept on the V axis (I = 0) is ε. A positive slope r would mean the voltage rises as more current is drawn. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.