In the circuit shown, a four-wire potentiometer is made of a $400 c m$ long wire, which extends between $A$ and $B$ . The resistance per unit length of the potentiometer wire is $r = 0.01 Ω / c m .$ If an ideal voltmeter is connected as shown with jockey $J$ at $50 c m$ from end $A$ , the expected reading of the voltmeter will be:

Question

In the circuit shown, a four-wire potentiometer is made of a

400 c m

long wire, which extends between

A

and

B

. The resistance per unit length of the potentiometer wire is

r = 0.01 Ω / c m .

If an ideal voltmeter is connected as shown with jockey

J

at

50 c m

from end

A

, the expected reading of the voltmeter will be:

Aicharya · Accepted Answer

From the given question we take,

Current in the wire, $I = \frac{V}{R} = \frac{1.5 + 1.5}{0.5 + 0.5 + 1 + (0.01 \times 400)} = 0.5 A$

Resistance of $50 cm$ long wire, $= 50 \times 0.01 = 0.5 Ω$

Reading $=$ Current $\times$ Resistance
$= 0.5 \times 0.5$
$= 0.25 V$

In the circuit shown, a four-wire potentiometer is made of a 400   c m long wire, which extends between…