JEE Main 2025 Jan 22 Shift 1, Physics Q3: Wheatstone Bridge, Ammeter, Voltmeter And Potentiometer

With the slider at the midpoint, the potentiometer wire is split into two halves of $0.5\Omega$ each. The lower half ($0.5\Omega$) is in parallel with $R_e=2\Omega$:

$R_{||}=\frac{0.5\times 2}{0.5+2}=\frac{1}{2.5}=0.4\Omega$.

The upper half ($0.5\Omega$) is in series with this combination:

$R_{eq}=0.5+0.4=0.9\Omega$.

Current from the 0.9 V source: $i=\frac{0.9}{0.9}=1.0$ A.