Q. The length of a potentiometer wire is 5m. An electron in this wire experiences a force of $4.8 \times 10^{- 19}$N, emf of the main cell used in potentiometer is
A) 3 V
B) 15 V
C) 1.5 V
D) 5 V
Explanation
(b) Force $=$Electric intensity $\times$charge
$= \frac{Potential\ diffsrence}{distance} \times charge$
$\therefore\ 4.8 \times 10^{- 19} = \frac{V}{5} \times {1.6 \times 10}^{- 19}$
or $V = 15$ volt
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.