Question

In the potentiometer arrangement shown in figure, null point is obtained at length $l$.

Column I		Column II
i	If $E_1$ is increased	p	$l$ should increase
ii	If $R$ is increased	q	$l$ should increase
iii	If $E_2$ is increased	r	$l$ should remain the same to again get the null point

Now, match the given columns and select the correct option from the codes given below.

• A. i - (q), ii - (p), iii - (r)
• B. i - (q), ii - (p), iii - (p)
• C. i - (p), ii - (q,) iii - (r)
• D. i - (r), ii - (p), iii - (q)

Answer 1

Answer: (B)

(b) For potentiometer circuit, $E=x{l}_1$
$x$ depends only on primary circuit
(i) $E_1\uparrow \Rightarrow x\uparrow \Rightarrow l_1\downarrow$ if secondary circuit remains same
(ii) $R\uparrow \Rightarrow x\downarrow \Rightarrow l_1\uparrow$ if secondary circuit remains same
(iii) $E_2\uparrow =l_1\uparrow$ if $x$ remains same