Four resistances, each of `10 Omega`, are connected to form a square as shown in (Fig. 3.52), find the equivalent resistance between the opposite corners `A and C`.
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Explanation

Resistance in the path `ADC = 10 Omega + 10 Omega = 20 Omega`
Resistance in the path `ABC = 10 Omega + 10 Omega = 20 Omega`
Since the resistances in the paths ADC and ABC are in parallel. Resistance between A and C, i.e.,
`(1)/( R)=(1)/(20)+(1)/(20)=(2)/(20)=(1)/(10)` or `R = 10 Omega`.