Archive for January, 2009

Jan-15th-2009

Repeater

In telegraphy an instrument for repeating the signals through a second line. It is virtually a relay which is operated by the sender, and which in turn operates the rest of the main line, being situated itself at about the middle point of the distance covered. In the simpler forms of repeater two relays are [...]

Jan-14th-2009

Abscissa

In a system of plane co-ordinates (see Co-ordinates) the distance of any point from the axis of ordinates measured parallel to the axis of abscissas. In the cut the abscissa of the point a is the line or distance a c. Fig. 1. AXES OF CO-ORDINATES

Jan-8th-2009

Zone, Polar

In medical electricity, the region surrounding the electrode applied to the human body.

Jan-8th-2009

Zone, Peripolar

In medical electricity, the region surrounding the polar zone, q. v.

Jan-8th-2009

Zinc Sender

An apparatus used in telegraphy for sending a momentary reverse current into the line after each signal, thus counteracting retardation.

Jan-8th-2009

Zincode

The terminal connecting with the zinc plate, or its equivalent in an electric circuit; the negative electrode; the kathode. A term now little used.

Jan-8th-2009

Zinc

A metal; one of the elements; atomic weight, 65.1; specific gravity, 6.8 to 7.2. microhms. Resistance at 0° C. (32° F.), per centimeter cube,   5.626 Resistance at 0° C. (32° F.), per inch cube,         2.215 Relative resistance (silver = 1),                    3.741 ohms. Resistance of a wire, 1 foot long, weighing 1 grain,   .5766 (a) 1 [...]

Jan-8th-2009

Zero, Thermometric

There are three thermometric zeros. In the Réaumur and centigrade scales, it is at the temperature of melting ice; in the Fahrenheit scale, it is 32° F. below that temperature, or corresponds to -17.78° C. The third is the absolute zero. (See Zero, Absolute.)

Jan-8th-2009

Zero, Potential

Conventionally, the potential of the earth. True zero potential could only exist in the surface of a body infinitely distant from other electrified bodies.

Jan-8th-2009

Zero, Absolute

From several considerations it is believed that at a certain temperature the molecules of all bodies would touch each other, their kinetic motion would cease, and there would be no heat. This temperature is the absolute zero. It is put at -273° C. (-459° F.) [Transcriber's note; The modern value is 0° Kelvin,  -273.15° C, [...]