Types of Thermometer

Different types of thermometers Galileo thermometer. AGalileo thermometer(orGalilean thermometer), named after Italian physicistGalileo Galilei, is athermometermade of a sealedglass cylindercontaining a clearliquidand a series of objects whose densities are such that they rise or fall as the temperature changes. By definition, Galileos thermometer is actually a thermoscope, not a thermometer. Gas thermometer Agas thermometermeasurestemperatureby the variation in hatful or pressure of a gas.One common apparatus is a ageless volume thermometer. It consists of a bulb connected by acapillary tubeto amanometer. The bulb is filled with a gas such that the volume of the gas in the bulb remains constant. The volume is related to temperature by k, known as Charless Law. The pressure of the gas in the bulb peck be obtained by measuring the level difference in the two arms of the manometer. Gas thermometers are often used to calibrate otherthermometers. alcoholic drink thermometerTheAlcoho l thermometerorspirit thermometeris an alternative to themercury-in-glass thermometer, and functions in a similar way. But unlike mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and pass on evaporate away fairly quickly. For the working temperature range, themeniscusor interface between the liquid is within the capillary. With increasing temperature, the volume of liquid expands and themeniscusmoves up the capillary. The typeset of themeniscusshows the temperature against an inscribed scale. Infrared thermometerInfrared thermometersinfertemperatureusing a portion of thethermal radiationsometimes calledblackbody radiationemitted by the object of measurement. Theyre sometimes calledlaser thermometersif alaseris used to help aim the thermometer, ornon-contact thermometersto describe the devices ability to measure temperature from a distance. By well-educated the amount of infrared energy emitted by the object and itsemissivity, the objects temperat ure can be determined most of the time. Mercury thermometer Amercury-in-glass thermometer, is athermometerconsisting ofmercuryin aglasstube.Calibrated marks on the tube allow thetemperatureto be read by the length of the mercury within the tube, which varies (nearly linearly) according to the temperature of the mercury. To increase the sensitivity, there is usually a bulb of mercury at the end of the thermometer which contains most of the mercury expansion and contraction of this volume of mercury is then amplified in the much narrower tire of the tube. The space above the mercury may be filled withnitrogenor it may be less than atmospheric pressure, which is normally known as avacuum.