Space between two concentric conducting spheres of radii a and b (b > a) is filled with a medium of resistivity ρ. The resistance between the two spheres will be: (a) (ρ)/(2π)(1/a + 1/b) (b) (ρ)/(4π)(1/a + 1/b) (c) (ρ)/(2π)(1/a - 1/b) (d) (ρ)/(4π)(1/a - 1/b)

Answer: (d). Current flows radially through spherical shells of area 4π r²: dR = (ρ dr)/(4π r²). R = (ρ)/(4π)∫abdr/r² = (ρ)/(4π)(1/a - 1/b) The answer is (d).

Space between two concentric conducting spheres of radii a and b (b >… | JEE Main 2019 (10 Apr, Shift 2)

Q50JEE Main 2019 · 10 APR · SHIFT 2Difficult

Ohm's Law, Resistivity & Temperature

Space between two concentric conducting spheres of radii a and b (b > a) is filled with a medium of resistivity $\rho$ . The resistance between the two spheres will be:

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Answer: (d)

Current flows radially through spherical shells of area $4\pi r^2$ : $dR = \dfrac{\rho\,dr}{4\pi r^2}$ .
$R = \dfrac{\rho}{4\pi}\int_a^b\dfrac{dr}{r^2} = \dfrac{\rho}{4\pi}\left(\dfrac{1}{a} - \dfrac{1}{b}\right)$
The answer is (d).

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Ohm's Law, Resistivity & Temperature question from JEE Main 2019 (10 Apr, Shift 2)

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