Question

The length of a potentiometer wire is $400 \, cm$ . Leclanche cell gets balanced against $150 \, cm$ length of the wire. What is the new balancing length, if the length of the wire is altered to $600 \, cm$ ?

• A. $225 \, cm$
• B. $300 \, cm$
• C. $250 \, cm$
• D. $200 \, cm$

Answer 1

Answer: (A)

Since resistance of remains same in both cases
$x\ell \, = \, x′\ell ′$
$\left(\frac{E}{400}\right)\left(150\right)= \, \left(\frac{E}{400}\right)\left(\ell ^{′}\right)$
or $\ell ^{′}= \, 225 \, cm$