3. Red blood cells can be modeled as spheres of 7.33 µm diameter with -2.55x10-12 C excess charge uniformly distributed over the surface. Find the electric field at the following locations, with radially outward defined as the positive direction and radially inward defined as the negative direction. (a) What is the vector electric field inside the cell at a distance of 3.10 um from the center? (b) What is the vector electric field just outside the surface of the cell?

The charge density of a non-uniformly charged sphere of radius 1.0 m is given as: For rs 1.0 m; p(r)= Po(1-4r/3) For r> 1.0 m; p(r)= 0, where r is in meters. What is the value of r in meters for which the electric field is maximum? 0.25 0.50 0.75 1.00 2.00 Other:

A non-conducting sphere 15.0cm in diameter has a total charge of 2.25µC distributed uniformly throughout its volume. Plot the magnitude of the electric field, E, as a function of the distance, r, from the center of the sphere, from r =0cm to r =30.0cm. (The graph must be madeon computer)

Question 17 In fair weather, the electric field in the air at a particular location immediately above the Earth's surface is 117 N/C directed downward. Imagine the surface charge density is uniform over the entire surface of the planet. What then is the magnitude of the net charge, in KC, of the whole surface of the Earth?