What should be the value of unknown resistance R so that equivalent resistance between P and Q is also R ?

Options

A. `3 Omega`
B. `sqrt(39) Omega`
C. `sqrt(69) Omega`
D. `10 Omega `

Answer

C

Explanation

`sqrt(69) Omega`
`R = 3 + (10 (3 + R))/(10+ (3+ R))`
`R = 3 + (30 + 10R)/(13 + R)`
13 R + `R^(2) = 39 + 3R + 30 + 10R `
`therefore R^(2) = 69`
`therefore R = sqrt(69) Omega`