JEE PYQ: Current Electricity Question 39
Question 39 - 2019 (08 Apr 2019 Shift 2)
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 $r = 0.01,\Omega$/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:
(1) 0.50 V
(2) 0.75 V
(3) 0.25 V
(4) 0.20 V
Show Answer
Answer: (3)
Solution
Resistance of potentiometer wire $= 0.01 \times 400 = 4,\Omega$. Current in wire $i = \frac{V}{R_T} = \frac{3}{4 + 0.5 + 0.57 + 1} = \frac{1}{2}$ A. $V = iR_{AJ} = \frac{1}{2} \times (0.01 \times 50) = 0.25$ V.
BETA
