# 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 voltlmeter will be: Option 1) 0.50 V Option 2) 0.75 V Option 3) 0.25 V Option 4) 0.20 V

$I=\frac{1.5+1.5}{1+1+R_{AB}}$

$R_{AB}=400 \times 0.01=4 \Omega$

$I=\frac{3}{6}=\frac{1}{2}=0.5A$

$Volmeter \;Reading=I \times R_{50 cm}$

$V=\left ( 0.5 \right )\times \left ( 0.01 \times 50 \right )$

$V=0.25 \;volt$

Option 1)

0.50 V

Option 2)

0.75 V

Option 3)

0.25 V

Option 4)

0.20 V

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