JEE PYQ: Current Electricity Question 61
Question 61 - 2019 (10 Jan 2019 Shift 1)
A potentiometer wire AB having length L and resistance $12,r$ is joined to a cell D of emf $\varepsilon$ and internal resistance $r$. A cell C having emf $\varepsilon/2$ and internal resistance $3r$ is connected. The length AJ at which the galvanometer as shown in fig. shows no deflection is:
(1) $\frac{11}{12}L$
(2) $\frac{11}{24}L$
(3) $\frac{13}{24}L$
(4) $\frac{5}{12}L$
Show Answer
Answer: (3)
Solution
$i = \frac{\varepsilon}{12r + r} = \frac{\varepsilon}{13r}$. $\frac{\varepsilon}{13r} \left(\frac{x}{L} \times 12r\right) = \frac{\varepsilon}{2}$. $x = \frac{13L}{24}$.
BETA
