Name the material used to transfer of charges from one body to other

Ahollow metal sphere has 6 cm and 11 cm inner and outer radii, respectively. the surface charge density on the inside surface is −100nc/m2. the surface charge density on the exterior surface is:

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

What are the applications of electromagnetic waves