A solid disk of radius R = 11 centimeter lies in the y-z plane with the center at the origin. The disk carries a uniformly distributed total charge Q = 65 µC. A point P is situated along the x-axis a distance 25 centimeter from the origin.

a. Write an equation for the surface charge density in terms of the total charge and radius of the disk.

b. Consider a thin ring of the disk of thickness dr placed a distance r from the center. Write an equation for the charge in this thin ring in terms of Q, R, r, and dr.

c. Find the electric potential at P in units of kilovolts, kV.

d. Find the electric field at the point P in units of mega Newton's per coulomb.