Question

When two cells of e.m.f 1.5 V and 1.1 V connected in series are balanced on a potentiometer, the balancing length is 260 cm. The balancing length, when they are connected in opposition is (in cm) ____________.

पर्याय

• 100

• 110

• 40

• 65

Answer 1

When two cells of e.m.f 1.5 V and 1.1 V connected in series are balanced on a potentiometer, the balancing length is 260 cm. The balancing length, when they are connected in opposition is (in cm) 40.

Explanation:

${\displaystyle \text{E}\propto l}$

${\displaystyle \frac{{\text{E}}_1+{\text{E}}_2}{{\text{E}}_1-{\text{E}}_2}=\frac{l_1}{l_2}}$

${\displaystyle \therefore \frac{1.5+1.1}{1.5-1.1}=\frac{260}{l_2}}$

${\displaystyle \therefore \frac{2.6}{0.4}=\frac{260}{l_2}}$

${\displaystyle \therefore l_2=\frac{260}{2.6}\times 0.4}$

${\displaystyle =40 \text{cm}}$