Explain briefly how knowing the electric field of a ring helps in calculating the field of a disk. Consider the algebraic expression for the electric field of a uniformly charged ring, at a location...

Explain briefly how knowing the electric field of a ring helps in calculating the field of a disk.

Consider the algebraic expression for the electric field of a uniformly charged ring, at a location on the axis of the ring. Q

is the charge on the entire ring, and ΔQ is the charge on one piece of the ring. Δθ is the angle subtended by one piece of

the ring (or, alternatively, Δr is the arc length of one piece). What is ΔQ, expressed in terms of given constants and an

integration variable? What are the integration limits?