A circle of 2.5 meter radius is made using a wire of uniform cross section and resistivity `1 m^(2)`. If resistance of this wire is `10 pi Omega` resistivity of the material of the wire is ........

Options

A. `4 pi Omega` m
B. `(0.25)/(pi) Omega`m
C. `2 Omega` m
D. `1 Omega` m

Answer

C

Explanation

` 2 Omega` m
`R = (l rho)/(A) " " therefore R = (2 pi r rho)/(A)`
`therefore rho = (RA)/(2 pi r) = (10 pi xx 1 )/(2pi xx 2.5) = 2 Omega` m