Problem 2.7 Find the electric field a distance z from the center of a spherical surface of radius R (Fig. 2.11), which carries a uniform charge density o. Treat the case z < R (inside) as well as z > R (outside). Express your answers in terms of the total charge q on the sphere. [Hint: Use the law of cosines to write r in terms of R and 0. Be sure to take the positive square root: VR? + z? – 2Rz = (R – 2) if R > z, but it's (z – R) if R < z.]

Problem 2.7 Find the electric field a distance z from the center of a spherical surface of radius R (Fig. 2.11), which carries a uniform charge density o. Treat the case z < R (inside) as well as z > R (outside). Express your answers in terms of the total charge q on the sphere. [Hint: Use the law of cosines to write r in terms of R and 0. Be sure to take the positive square root: VR? + z? – 2Rz = (R – 2) if R > z, but it's (z – R) if R < z.]