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Illustration of a thin hollow cylinder. It resembles a washer and is often referred to as a disc.

Hollow Cylinder

Illustration of a thin hollow cylinder. It resembles a washer and is often referred to as a disc.

Illustration of a narrow right circular cylinder (with the height much smaller than the diameter) resting on its side/edge. This could also be described as a round disc.

Narrow Cylinder on Side

Illustration of a narrow right circular cylinder (with the height much smaller than the diameter) resting…

Illustration of 2 narrow right circular cylinders with equal heights (thickness) and different diameters. Both cylinders (discs) are resting on a side/edge.

2 Narrow Cylinders on Their Sides

Illustration of 2 narrow right circular cylinders with equal heights (thickness) and different diameters.…

"Electrification produced by rubbing dissimilar bodies together and then separating them. If the insulated glass and leather discs A and B be rubbed together, but not separated, no signs of electrification can be detected; but if the discs be drawn apart a little distance the space betwen them is found to be and electric field, and as they separate farther and farther, electric forces will be found to exist in more and more of the surrounding space, the electrification being indicated by 'lines of force.' " -Hawkins, 1917

Electrification

"Electrification produced by rubbing dissimilar bodies together and then separating them. If the insulated…