Question

In a potentiometer a cell of emf 1.5 V gives a balanced point at 32 cm length of the wire. If the cell is replaced by another cell then the balance point shifts to 65.0 cm then the emf of second cell is

• A. 3.05 V
• B. 2.05 V
• C. 4.05 V
• D. 6.05 V

Answer 1

Answer: (A)

3.05 V

Answer 2

: Here, in the balance condition of potentiometer

$\frac{\varepsilon_{1}}{\varepsilon_{2}} = \frac{l_{1}}{l_{2}}$

$\varepsilon_{1} = 1.5V,l_{1} = 32cm,l_{2} = 65cm$

$\therefore\varepsilon_{2} = \varepsilon_{1} \times \frac{l_{2}}{l_{1}} = 1.5 \times \frac{65}{32} = 3.05V$