When a wire of uniform cross-section a length / and resistance R is bent into a complete circle, the resistance between any two of diametrically opposite points will be

It is obvious from fig. that two wires of resistances R / 2 and R / 2 are connected in parallel between two points A and 8. Therefore, the equivalent resistance between two diametrically opposite points will beReq=R1R2R1+R2=(R/2)×(R/2)(R/2)+(R/2)  or  Req=R4