Three long concentric conducting cylindrical shells have radii `R,2R` and `2sqrt(R )`. Inner and outer shells are connceted to each other. The capacitance across middle and inner shells per unit length is:

Options

A. `( (1)/(3) in _0)/( 1n 2) `
B. ` ( 6pi in _0)/( 1n 2 ) `
C. ` ( pi in _ 0 )/( 2 1n 2 )`
D. None

Answer

B