Table of Contents
How does a glass stem thermometer measure temperature?
It consists of a sealed glass tube with a small internal diameter (like a lumen) connected to a reservoir. Increasing the temperature expands and pushes up the fluid in the reservoir and tube. A scale on the tube and the location of the expanded fluid indicate the temperature, see Fig. 8.3A.
What is the principle used in thermometers?
These liquid thermometers are based on the principal of thermal expansion. When a substance gets hotter, it expands to a greater volume. Nearly all substances exhibit this behavior of thermal expansion. It is the basis of the design and operation of thermometers.
How does a glass mercury thermometer work?
In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Mercury thermometers can be used to determine body, liquid, and vapor temperature.
What is an advantage of the glass stem thermometer quizlet?
One advantage of the glass-stem thermometer is that it: Does not rely on any mechanical or electronic device that can malfunction.
How does a glass thermometer work?
A glass thermometer consists of a stem and bulb. When the thermometer bulb is placed next to body tissue, the mercury absorbs some of the body’s heat. As the mercury gets warmer, it expands. Since the mercury has no more room in the bulb, some of the mercury is forced into the shaft.
Why is glass used in thermometers?
Glass has a very low coefficient of thermal expansion. This is the reason why thermometer bulb or for a matter of fact entire thermometer is made up of glass. Due to low coefficient of thermal expansion, when the thermometer undergoes a large temperature change it will have minimal change in dimensions.
On what principle does a bimetal strip operate?
Bimetal thermometers work on the principle that different metals expand at different rates as they are heated. By using two strips of different metals in a thermometer, the movement of the strips correlates to temperature and can be indicated along a scale.
What is the basic principle inverted the working of thermometer?
A thermometer has a glass tube sealed at both ends and is partly filled with a liquid like mercury or alcohol. As the temperature around the thermometer’s bulb heats up, the liquid rises in the glass tube. When it is hot, the liquid inside the thermometer will expand and rise in the tube.
What liquids can be used in a glass stem thermometer quizlet?
A Liquid-in-glass thermometer is a glass tube with a bulb at one end filled with the liquid and a scale fastened to or etched on the glass tube. The liquid is usually mercury or alcohol. The freezing and boiling points of mercury are -39 °C and 357 °C, respectively. Alcohol can be used down to -62°C.
What is a thermocouple made out of?
Common thermocouple materials include copper/constantan (Type T), iron/constantan (Type J), and chromel/alumel (Type K). When several thermocouples, made of the same materials are combined in series, they are called a thermopile.
What is the principle of a liquid in glass thermometer?
The principle used to measure temperature is that of the apparent thermal expansion of the liquid. A typical liquid-in-glass thermometer is shown in the figure below.
What should the stem of a glass thermometer look like?
The stem should have a plain front and enamel back in yellow. All graduation lines, figures, and letters should be clear-cut, distinct, and filled with a permanent pigment of suitable color.
How is the firing temperature of a glass thermometer calculated?
If a mercury in glass thermometer is used, the observed firing temperature and the final temperature must be corrected as prescribed by the certificate issued with the instrument. This is calculated from the weight of the length of cotton, and the heat of combustion of cotton, which is a pure form of cellulose.
Is it safe to use liquid in glass thermometer?
Reading temperature via liquid-in-glass thermometers call for brilliant eyesight. Liquid element contained in a glass thermometer may be perilous or risky to health owing to their potential chemical spills. These thermometers display temperature either in Celsius or Fahrenheit scales.