A
dial is generally a flat surface, circular or rectangular, with numbers or similar markings on it, used for displaying the setting or output of a
timepiece,
radio,
clock,
watch, or
measuring instrument. There are many instruments used in scientific and industrial applications that use dials with pointers as indicators of a specific physical property. Typical examples include
pressure and vacuum gages, fluid-level gages (for fuel, engine oil, and so on),
voltmeters and
ammeters,
thermometers and
hygrometers,
speedometers and
tachometers, and
indicators (distance amplifying instruments).