A wire of resistance 12   Ω  m−1 is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite point s, A and B, as shown in the figure, is

Circumference of circle 2  ×  π 10100  =  2π10 = π5Resistance of wire =  12 × π5 = 12π5Resistance of each section = 12π10  Ω∴   Equivalent resistanceReq  =  12π10 ×  12π1012π10 +  12π10  =  6π10  =  0.6  π  Ω