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Space between tow concentric spheres of radii `r_(1) and r_(2)` such that `r_(1) lt r_(2)` is filled with a material of resistivity `rho`. Find the resistance between inner and outer surface of the material A. `(r_(1))/(r_(2))(p)/(2)`B. `(r_(2)-r_(1))/(r_(1)r_(2))(p)/(4pi)`C. `(r_(1)r_(2))/(r_(2)-r_(1))(p)/(4pi)`D. none of these. |
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Answer» Correct Answer - B Since, `R=rho(l)/(a) therefore R=rho=(dl)/(4pil^(2))` (where l is any radius and dl is small element). `R=(rho)/(4pi) underset(r_(1))overset(r_(2))(int)(dl)/(l^(2))=(rho)/(4pi)[-(1)/(l)]_(r_(1))^(r_(2))=(rho)/(4pi)[(1)/(r_(1))-(1)/(r_(2))]` `R=[(r_(2)-r_(1))/(r_(1)r_(2))](rho)/(4pi)` |
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