Hello,
I am looking at an example of finding the charge of a uniform disk with a continuous charge on the surface.
They go about the problem by finding the infinitesimal charge of concentric rings
dq = σdA = σ(2πr dr)
The part I don't understand is that they use the area as 2πr dr? The area of a ring would be ∏(R2^2 - R1^2), right?
I am looking at an example of finding the charge of a uniform disk with a continuous charge on the surface.
They go about the problem by finding the infinitesimal charge of concentric rings
dq = σdA = σ(2πr dr)
The part I don't understand is that they use the area as 2πr dr? The area of a ring would be ∏(R2^2 - R1^2), right?