The resistance between point `A` and `C` below is

Options

A. `3 Omega`
B. `4 Omega`
C. `2 Omega`
D. `8 Omega`

Answer

C

Explanation

When a battery is connected across `A` and `C` no current flow through arm `BO` Thus the resistance of arm `BD`. Thus the resistance of arm BD is ineffective. Hence the resistances of arms `ABC,AC and ADC` each `6 Omega`are in parallel .Thus effective resistance `R_(P)` will be
`(1)/(R_(p)) = (1)/(6) + (1)/(6) + (1)/(6) + (3)/(6) = (1)/(2) or R_(P) = 2 Omega`