Q. In a potentiometer experiment two cells of e.m.f.’ s $E_{1}$ and $E_{2}$ are used in series and in conjunction and the balancing length is found to be $58\ cm$ of the wire. If the polarity of $E_{2}$ is reversed, then the balancing length becomes $29\ cm.$ The ratio $\frac{E_{1}}{E_{2}}$ of the e.m.f. of the two cells is
A) 1 : 1
B) 2 : 1
C) 3 : 1
D) 4 : 1
Explanation
(c) $\frac{E_{1}}{E_{2}} = \frac{l_{1} + l_{2}}{l_{1} - l_{2}} = \frac{58 + 29}{58 - 29} = \frac{3}{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.