Question

A potentiometer has a driving cell of negligible internal resistance. The balancing length of a Daniel cell is 5 m. If the driving cell had internal resistance, the balancing length of the same Daniel cell would have been

• A. More
• B. Less
• C. Same
• D. Cannot be said from the data

Answer 1

The correct option is A More

A potentiometer has a driving cell of negligible internal resistance. The balancing length of a Daniel cell is 5 m.

$\therefore \frac{r+R}{R}=\frac{L}{l}$

$\therefore r=\frac{R(L-l)}{l}$

Where $R=R_d+r_d$

where $r_d$ is internal resistance of Daniel cell

hence,the balancing length of the same Daniel cell would have been more.