Calculate the resistance between the points A and B of the networks shown in figure

Explanation

Here, `5/5 = 5/5`, so the resistance of `20 Omega` is ineffective. The equivalent circuit is as shown in figure

Now we have, resistance of `(5+5)Omega, (5+5)Omega` and `20 Omega` in parallel between points A nad B. Therefore the effective resistance (R) between A and B is
`1/R = 1/10 + 1/10 + 1/20 = 5/20 = 1/4 or R= 4 Omega`