First slide

potentiometer

Question

For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.
The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E₁.

Moderate

A

$1.5 Ω$
B

$2 Ω$
C

$0.5 Ω$
D

$1 Ω$

Solution

Let $λ$ be resistance per unit length of wire AB. When k is opened, $I ({λx}_{1}) = E_{1}$ ….(1)
After k is closed: $I ({λx}_{2}) = E_{1} - ir$ ….(2)
$\begin{array}{l} i = \frac{E_{1}}{R + r} \\ \Rightarrow r = (\frac{x_{1}}{x_{2}} - 1) R (\frac{0 .75}{0 .60} - 1) = 6 = 1 .5 Ω \end{array}$ ….(3)

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App