A: Thomas Paine believed that the American army would become the strongest in the world, that America would achieve independence from Britain with a strong ar... Full Answer > Filed Under:
How DVDs Work. DVDs are of the same diameter and thickness as CDs, and they are made using some of the same materials and manufacturing methods. Like a CD, the data on a DVD is encoded in the form of small pits and bumps in the track of the disc. A DVD is composed of several layers of plastic, totaling about 1.2 millimeters thick. Each layer is created by injection molding polycarbonate plastic.
Thatâs why CD-ROMs top out at about 650-700 MB of data, while DVDs can hold multiple gigabytes of data. Since the pits are more tightly written on a DVD disc, the mechanism in the drive for reading them also has to be finer and more precise. Thatâs the main reason that DVD drives cost more than CD-ROM drives. DVD drives can also read regular CD-ROM discs with no problem, since the difference is mostly in the spacing.