Noncontact capacitive sensors work by measuring changes in an electrical property called capacitance. Capacitance describes how two conductive objects with a space between them respond to a voltage difference applied to them. When a voltage is applied to the conductors, an electric field is created between them causing positive and negative charges to collect on each object (Fig. 1).
You are working on a word processing document, and you need access to an item you just copied to the clipboard. You wonder if there is a way to get to the clipboard quickly. The clipboard is a storage area within an operating system for items you copy or cut from a document, website or other computer application. Accessing the clipboard on your computer is not tricky. In Windows XP, the clipboard can be accessed through the My Computer selection.
Bulletin boards are often made of a material such as cork to facilitate addition and removal of messages, as well as a writing surface such as blackboard or whiteboard. A bulletin board which combines a pinboard (corkboard) and writing surface is known as a combination bulletin board. Bulletin boards can also be entirely in the digital domain and placed on computer networks so people can leave and erase messages for other people to read and see, as in a Bulletin board system.