ABSTRACT
A change in temperature of a substance can often result in a change in one or more of its physical properties. Thus, although temperature cannot be measured directly, its effects can be measured. Some properties of substances used to determine changes in temperature include changes in dimensions, electrical resistance, state, type and volume of radiation and colour. Temperature-measuring devices available are many and varied. A liquid-in-glass thermometer uses the expansion of a liquid with increase in temperature as its principle of operation. Atypical liquid-in-glass thermometer is consists of asealed stem of uniform small-bore tubing, called a capillary tube, made of glass, with a cylindrical glass bulb formed at one end. The operation of a liquid-in-glass thermometer depends on the liquid expanding with increase in temperature and contracting with decrease in temperature. Thermocouples use the electromotive force set up when the junction of two dissimilar metals is heated.
