Question

In a potentiometer experiment, the balancing point will a cell is at 560 cm. When an external resistance of 10 W is connected in parallel to the cell, the balancing length changes to 412 cm. The internal resistance of the cell in ohms is :

• A. 3.6
• B. 2.4
• C. 1.2
• D. 0.6

Answer 1

Answer: (A)

3.6

Answer 2

l₁ = 560 cm, l₂ = 412 cm, R = 10 W

r = R$\left( \frac{\mathcal{l}_{1}}{\mathcal{l}_{2}} - 1 \right)$, r = $10\left( \frac{560}{412} - 1 \right) = 3.6\Omega$