In the circuit shown, a four-wire potentiometer is made of a 400 cm long wire, which extends between A and B. The resistance per unit length of the potentiometer wire is r = 0.01 Ω/cm. If an ideal voltmeter is connected as shown with jockey J at 50 cm 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 cm long wire, which extends between A and B. The resistance per unit length of the potentiometer wire is r = 0.01 Ω/cm. If an ideal voltmeter is connected as shown with jockey J at 50 cm from end A, the expected reading of the voltmeter will be : (A) 0.20 V (B) 0.25 V (C) 0.75 V (D) 0.50V

Tardigrade Admin · Accepted Answer

Resistance of wire AB = 400 × 0.01 = 4 Ω i = (3/6) = 0.5 A Now voltmeter reading = i (Resistance of 50 cm length) = (0.5 A) (0.01 × 50) = 0.25 volt

0.20 V

0.25 V

0.75 V

0.50V

Resistance of wire AB=400×0.01=4Ω i=63​=0.5A Now voltmeter reading = i (Resistance of 50 cm length) =(0.5A)(0.01×50)=0.25 volt

Resistance of wire $A B = 400 \times 0.01 = 4Ω$
$i = \frac{3}{6} = 0.5 A$
Now voltmeter reading = $i$ (Resistance of 50 cm length)
$= (0.5 A) (0.01 \times 50) = 0.25$ volt