In the circuit given below, the value of resistance X, when the potential difference between the point B and D is zero, will be

Options

A. `9Omega`
B. `8Omega`
C. `4Omega`
D. `6Omega`

Answer

B

Explanation

`P=15+6 = 21Omega, Q= (8X)/(8+X)+3`
`R=15+ (6 xx 6)/(6+6) = 18Omega, S= 4+ (4 xx 4)/(4+4)=6Omega`
As, `(P)/(Q)= (R )/(S)`, so `Q= (PS)/(R )=(21 xx 6)/(18)= 7Omega`
`3+ (8X)/(8+X) =7 rArr X=8Omega`