A wire of resistance 5 Ohms is bent in the form of a closed circle. What is the effective resistance between the two points at ends of any diameter of the circle?

Explanation

The length of the wire between two points at the ends of a diameter is half of the whole wire. The resistance of a conductor is directly proportional to its length.
Thus two resitance `(5)/(2)Omega` will be in a parallel.
Let R is the effective resistance.
`(1)/(R)= (2)/(5)+ (2)/(5)`
`implies (1)/(R)= (4)/(5)`
`:. R= (5)/(4)= 1.25Omega`