A solid conducting sphere of radius a has a net positive charge 2Q. A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge –Q. The surface charge density on the inner and outer surfaces of the spherical shell will be

(1) $-\frac{2Q}{4\pi {b}^{2}},\frac{Q}{4\pi {c}^{2}}$

(2) $-\frac{Q}{4\pi {b}^{2}},\frac{Q}{4\pi {c}^{2}}$

(3) $0,\frac{Q}{4\pi {c}^{2}}$

(4) None of the above

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Concept Questions :-

Gauss law

(1) Surface charge density (σ)

So ${\sigma }_{inner}=\frac{-2Q}{\text{\hspace{0.17em}}4\pi {b}^{2}}$ and ${\sigma }_{Outer}=\frac{Q}{\text{\hspace{0.17em}}4\pi {c}^{2}}$

Difficulty Level:

• 48%
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• 9%