The resistance of a semicircle shown in fig. Between its two end faces is (Given that radial thickness `=3cm`, axial thickness `=4cm`, inner radius `=6cm` and resistivity `=4xx10^(-6)Omegacm`)

Options

A. `24.15xx10^(-6)Omega`
B. `7.85xx10^(-7)Omega`
C. `7.85xx10^(-6)Omega`
D. `7.85xx10^(-5)Omega`

Answer

C

Explanation

Here, `A=4cmxx3cm=12cm^(2)`
`l=pir=pi(6+(3)/(2))=pixx7.5cm`
`R=(rhol)/(A)=(4xx10^(-6)xxpixx7.5)/(12)`
`=7.85xx10^(-6)ohm`.