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.
A Blu-ray disc is a form of optical disc. It looks the same as a DVD, but can store about six times as much information as a standard DVD. Because they can hold so much more information, Blu-ray discs can provide high-definition audio and video for output on HD TVs and surround sound systems, while an ordinary DVD cannot.