ramu n
Last Activity: 14 Years ago
If we consider the disk as a set of concentric rings, sum the contributions of all rings making up the disk. By symmetry, the field at an axial point must be along the central axis. The ring of radius r and width dr shown in Figure above has a surface area equal to 2*pi*r*dr. The charge dq on this ring is equal to the area of the ring multiplied by the surface charge density: dq=2*pi*r*dr.

