# All Science Fair Projects

## Science Fair Project Encyclopedia for Schools!

 Search    Browse    Forum  Coach    Links    Editor    Help    Tell-a-Friend    Encyclopedia    Dictionary

# Science Fair Project Encyclopedia

For information on any area of science that interests you,
enter a keyword (eg. scientific method, molecule, cloud, carbohydrate etc.).
Or else, you can start by choosing any of the categories below.

# Sink

In plumbing, a sink is a bowl-shaped fixture, usually made of porcelain (or, especially in the kitchen, stainless steel), that is used for washing hands or small objects such as dishes, nylons, socks or underwear. Old sinks were often made of enameled steel or cast iron. In American plumbing parlance, a bathroom sink is known as a lavatory. Sinks generally have faucets, usually cold and hot, and a drain. When a sink becomes stopped-up or clogged, a person will often resort to use of chemical drain cleaner or a plunger.

In electromagnetic theory sink and source are respectively the termination or supply of current flow; the divergence of the current density is their negative and positive, respectively.

More generally this idea can be applied to vector fields other than current density; for example, mass is a sink of gravitational field strength.

A Transistor-transistor logic (TTL) circuit will "sink" current when the circuit is a logic "0" (grd) and "source" current at a logic "1" (+5vdc).

[These terms are far more generally used than just in digital electronics. Indeed, they antedate digital electronics. They are used in thermodynamics, which originated in the 19th century, and also for other physical systems such as rivers. Would some physicist complete this article?]

DATE: [04-07-30] Physicist writes: The concepts of sink and source can also be viewed as the physical interpretation of poles and singularities of a complex valued function. The function may define an electrostatic field potential, as mentioned previously, where the positive pole(s) of such a function form the source and negative pole(s) form a sink in the regions defined by a conformal mapping or residue integral. As such, the Laplacian is satisfied since the function becomes analytic outside the singular points and hence the electric field is then defined in real space with the poles being the supply and termination points.

In communication software, a sink enforces message policies.

Other uses of the general scientific concept of a sink are the heat sink and the CO2 sink.

03-10-2013 05:06:04