Question

In the circuit shown in the figure, the value of Resistance X, when potential difference between the points B and D is zero will be

Answer 1

Potential between B and D = 0
$\therefore$ The wheatstone bridge is balanced.
$\therefore$ Resistance between B and C
$\therefore \frac{ResistancebetweenAandB}{ResistancebetweenCandD}=\frac{ResistancebetweenBandC}{ResistancebetweenCandD}$
$\therefore \frac{21}{18}=\frac{811x+3}{6}$
$\therefore \frac{7}{6}=\frac{\frac{8x}{8x+x}+3}{6}$
$\therefore \frac{8x}{8+x}=4$
$\therefore 8x=32+4x$
$\therefore 4x=32$
$\therefore x=8\Omega$