In the figure given below find the resistance between points A and B. Both the circle and the diatmeter are made of uniform wire of resistance `r Omega` per meter. The length AB is 2 metre.

Options

A. 0.88 r
B. 0.68 r
C. r
D. 2r

Answer

A

Explanation

Let a be the radius of circle. Now, resistances `pi` a r, 2 ra and ` pi a r`, are connected in parallel.
Given ` 2 a = 2m :.a=1m`
`:.(1)/(R_(p))=(1)/(pi r)+(1)/(2 r)+(1)/(pi r) rArr R= 0.88 r`