Clock

A clock (from the Latin cloca, "bell") is an instrument for measuring time. A clock is usually a physical instrument; an especially accurate one is called a chronometer. The clock in its modern form (24 hour clock) has been in use since at least the 14th century. Clock can refer to an abstract system of time measurement (see calendar for other measurements). Modern clocks define constant units of time: an hour is always sixty minutes, of sixty seconds each.

Types

There are two major types of clocks.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Analog clocks

Analog clocks may be mechanical or have a quartz movement. A clock face is the part of an analog clock that tells time through the use of a fixed numbered dial or dials and moving hand or hands. It usually has a circular scale of 12 hours, which also serves as a scale of 60 minutes, and often also as a scale of 60 seconds. The analog clock with digital display emulates a digital clock but with an analog movement. The ultimate analog clock is the sundial, which tracks the sun continuously, registering the time by the shadow of its gnomon.

Related Topics:
Analog - Mechanical - Quartz movement - Clock face - Analog - Hour - Minute - Second - Analog clock with digital display - Sundial - Gnomon

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Digital clocks

Digital clocks use electronic methods of keeping time, typically the 60 hertz oscillation of AC power or a crystal oscillator as in a quartz movement. A digital clock typically displays a numerical hour range of 0-23, or 1-12 (with an indication of AM or PM) using an LCD or LED display, although digital versions of analog-style faces exist.

Related Topics:
Digital clock - Hertz - AC power - Crystal oscillator - Quartz movement - Digital - AM or PM - LCD - LED

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~