Question

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

• A. $-\frac{2Q}{4\pi b^2},\frac{Q}{4\pi c^2}$
  
  
• B. $-\frac{Q}{4\pi b^2},\frac{Q}{4\pi c^2}$
  
• C. $0,\frac{Q}{4\pi c^2}$
  
• D. $Noneofthese$
  

Answer 1

The correct option is A $-\frac{2Q}{4\pi b^2},\frac{Q}{4\pi c^2}$



Surface charge density \( (\sigma )=\frac{Charge}{Surface~area}\)

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