Question 455: Current Electricity

Question

In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is 3 : 2, the difference in the balancing length of the potentiometer wire in above two cases will be ___________ cm.

Accepted Answer

At balancing point, we know that emf is proportional to the balancing length. i.e.,
emf $$\propto$$ balancing length
Now, let the emf's be 3$$\varepsilon $$ and 2$$\varepsilon $$.
$$\Rightarrow$$ 3$$\varepsilon $$ = k(75) ..... (1)
and 2$$\varepsilon $$ = k(l) ....... (2)
$$\Rightarrow$$ l = 50 cm
$$\Rightarrow$$ Difference is (75 $$-$$ 50) cm = 25 cm.

Current Electricity

Choose the correct answer: