Identify the sensor, signal conditioner and display elements of a measurement system such as mercury-in-glass thermometer. Identify the input and output parameters.

Question

What will be an ideal response?

Answer 1

A mercury-in-glass thermometer, invented by Daniel Fahrenheit, is a thermometer consisting of mercury in a glass tube. Calibrated marks on the tube allow the temperature to be read by the length of the mercury within the tube, which varies according to the heat given to it. 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 bore of the tube. The space above the mercury may be filled with nitrogen or it may be less than atmospheric pressure, which is normally known as a vacuum. These devices were used extensively to measure temperatures in a wide variety of settings from the 1700s until the 20th century, when concerns about the health risks of mercury exposure led many nations to place restrictions on mercury-in-glass thermometers. Medical use of these instruments is largely restricted. The input parameter is heat. The output of the measurement system is the display of temperature. The temperature could be displayed in an analog form or digital form. The more sophisticated instrument may contain a signal conditioner embedded in a microprocessor.