a uniform wire of resistance 36 ohm is bent in tne form of a circle .calculate the effective resistance across the points A and B.

Let L = length of the wire

Now resistance per unit length of the wire = 36/L 

360^o subtends an wire length L

1^o subtends a length of = L/360

30^o subtends a  length of = L×(30/360 = L/12

Now resistance of the wire of length L/12 = (L/12)×(36/L) = 3 Ω