The question I need to be answered is 3.4.2 but it references the other two. I am working on 3.4.4 as well so if you could do that one as well I would appreciate it so I can check my work please and thank you!

3.2.4. A ring of charge of radius a has a linear charge density of _l C/m that is uniformly distributed around the ring. Determine the electric field at a distance d along a line perpendicular to the ring and centered on it. Evaluate this result for a distance much greater than the radius of the ring. This result at a large distance away should be reduced to that for a point charge. Why?

3.2.5. Determine the electric field of a disk of charge of radius a having a uniform charge distribution of C/m³ over its surface at a distance d away from its center and on a line through its axis. You will need the integral r/(d² - r²)^3/2dr = -1/(d² - r²) Evaluate this area, at a distance much larger than the radius of the disk. This result at a large distance should be reduced to that for a point charge. Why? [E = _s/2₀[1 - d/(d² - a²)a_z, E = a² _s/4₀d²a_z da. At large distances away, the disk of charge can be thought of as a point charge equal to the total charge contained in the disk: Q = a_s]

3.4.2. For the problem of a ring of charge in Problem 3.2.4 and the disk of charge in Problem 3.2.5, can Gauss' law be used to determine the electric field at a distance from the center and on a line perpendicular to the ring or disk? If not, why not?

3.4.4. A volume charge density = k/r C/m³ exists in a spherical region a r = b. Determine the electric field intensity vector.

[E_r = k(b² - a²)/2₀r² for r b, E_r = 0 for r 5a, E_r = k/2₀,(1 - a²/r²) for a r b]