A clock is an instrument
which is used to indicate, keep and coordinate time. It is one of the
oldest human inventions. The time keeping element in every clock is a
harmonic oscillator which is a physical object that vibrates repetitively
at a precise constant frequency. This oscillator can be a pendulum, a
tuning fork, a quartz crystal or the vibration of electrons in atoms as
they emit microwaves. Clocks and watches can be divided into two broad
categories – analog and digital. These categories are divided based on the
way time is displayed.
Analog: Analog clocks are available in all shapes and sizes and they indicate time using arrows or hands usually 3 hands/arrows. These clocks have a fixed dial which has calibrations into sixty markings along their conferences, indicating 12 hours. The 12 hours are further calibrated into 60 markings, each indicating a minute. The three hands or arrows rotate across the dial to indicate the passing hours and minutes.
Digital: Digital clocks employ LCD (liquid crystal display), LED (light emitting diodes) or VFD (variable frequency drive) to display time. These clocks indicate times in hours, minutes and seconds. They can display either a 12-hour format or the 24-hour format. Some digital clocks even indicate the date and day of the week also. Digital clocks can be powered by a quartz crystal or AC power.
Sundials: These can be
considered to be the first clocks. They are primitive time-telling devices
and they indicate the position of the sun in the sky. This device uses a
shadow-casting object which could be a thin rod, to determine the position
of the sun at the particular time of the day. It indicates the time by
casting a shadow on a flat surface with markings that usually correspond to
the hours of the day however, it cannot measure time after sunset or on
cloudy days. Sundials can either be horizontal or vertical.
Water clocks: These time measuring instruments came after the existence of the sundial. With this instrument, time is measured by the regulated flow of liquid from one vessel into another and the amount is then measured. The modern water clock keeps time by a calibrated pendulum which is powered by a water stream piped in from the clock's reservoir.
• The clock can be seen as
one of the most important devices of all civilization
• Clocks make it easier to organize events and coordinate activities.
• They can be used as decorating pieces as they can add more meaning and character to the overall décor of your living or working space.
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