For what value of unknown resistance $X$, the potential difference between $B$ and $D$ will be zero in the circuit shown in the figure ............... $\Omega$
A$4 $
B$6 $
C$2 $
D$5 $
Medium
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B$6 $
b For balanced Wheatstone bridge $\frac{P}{Q} = \frac{R}{S}$
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