Density, density, density. (a) A charge -338e is uniformly distributed along a circular arc of radius 6.70 cm, which subtends an angle of 41o. What is the linear charge density along the arc? (b) A charge -338e is uniformly distributed over one face of a circular disk of radius 3.80 cm. What is the surface charge density over that face? (c) A charge -338e is uniformly distributed over the surface of a sphere of radius 2.20 cm. What is the surface charge density over that surface? (d) A charge -338e is uniformly spread through the volume of a sphere of radius 3.30 cm. What is the volume charge density in that sphere?