JEE Main20198 Apr 2019Evening ShiftPhysicsCurrent ElectricityActual
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:
Options
- A0.50   V
- B0.25   V
- C0.75 V
- D0.20 V
Correct answer
B. 0.25   V
Step-by-step solution
From the given question we take, Current in the wire, I = V R = 1 . 5 + 1 . 5 0 . 5 + 0 . 5 + 1 + 0 . 01 × 400 = 0 . 5   A Resistance of 50   cm long wire, = 50 × 0 . 01 = 0 . 5   Ω Reading =   Current × Resistance = 0.5 × 0 . 5 = 0.25   V