4. 16 The diagram shows a liquid-in-glass thermometer. The temperature range is −80 to +330 °C depending on the liquid. What changes will produce the greatest increase in sensitivity? Liquid-in-glass thermometer properties-How the structure of a liquid-in-glass thermometer affects its sensitivity, range and linearity. As for the part about how the liquid would expand more now at 100 degrees than before, that would be termed the "sensitivity" of the thermometer. The measuring sensitivity of liquid-in-glass thermometers increases with the amount of liquid in the thermometer. The more liquid there is, the more liquid will expand and rise in the glass tube. [1] (b) (i) The graduations on a liquid-in-glass thermometer are equally spaced. To the left is a labelled diagram of a thermometer, you don't need to know all of the different parts of a thermometer, but I included it to help you understand. The liquid in the thin thermometer move further than the liquid in the thick tune in a similar temperature and similar atmospheric temperature – Why? A common range for liquid-in-glass thermometers is from –10 °C to 110 °C. Using a thermometer with a smaller bulb – A smaller bulb contains less mercury and therefore absorbs heat in a shorter moment in time. Their sensitivity is based upon the reversible thermal expansion characteristics of the liquid in comparison to the glass. 2. We also use third-party cookies that help us analyze and understand how you use this website. Types of Liquid-In-Glass Thermometers [] Introduction []. What do you mean by Sensitivity of a Thermometer? They are considered inapt for applications involving extremely high or low temperatures. lowest temperature = .....[1] (c) A second liquid-in-glass thermometer has the same range but it has a greater sensitivity. Liquid-in-Glass Thermometers. 3. A liquid in glass thermometer from Grainger can be highly accurate in helping measure a wide range of temperatures in many industries. Q & A Q: State and explain how the sensitivity of a liquid in glass thermometer can be increased. The sensitivity of a liquid-in-glass thermometer depends on the volume of liquid used and the diameter of the bore of the thermometer. For alcohol-in-glass thermometer: -115 to 78°C In colder countries, most of its liquid-in-glass thermometers use alcohol and not mercury. Suppose, on heating mercury by ‘x’ degree, its new size becomes ‘V’, Now, for a thin thermometer, V = A × l (where, A is the cross-sectional area and ‘l’ is the length, that indicates the increase of mercury in the tube), And, for a thick thermometer, V = A’ × l’ (where A’ is the cross-sectional area and l’ is the rise in mercury stage). The range of a liquid-in-glass thermometer is limited by the length of the thermometer and can be increased by: increasing the diameter of the capillary – this means that the liquid will not expand as … The size of this affects its sensitivity to changes in temperature, the thinner the more sensitive it will be, because the mercury will come into contact with the cold or heat more quickly. Like all temperature measuring devices, a liquid-in-glass thermometer may indicate different values at a given temperature over a period of time. The sensitivity of a mercury thermometer can be increased by using a smaller mercury bulb, thinner wall and smaller bore. The mercury thermometer is one example of liquid thermometers. But opting out of some of these cookies may affect your browsing experience. It is inside the glass body of the thermometer and is connected to the bulb. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Structure and advantages of a thermocouple. It is mandatory to procure user consent prior to running these cookies on your website. This type of thermometer was developed by a German based physicist named Daniel Gabriel Fahrenheit.It consists of mercury as a liquid filled in a glass tube. GCSE Keywords: Bulb, Thread diameter, Liquid, Glass thickness. This website uses cookies to improve your experience. For the equal spacing of the graduations to be correct, state: 1. an assumption that is made about the liquid in the thermometer 2. an assumption that is made about the structure of the thermometer. A increase the internal diameter of the tube containing the liquid thread B increase the internal volume of the glass bulb and the volume of the liquid A glass bulb with thinner wall – Heat can be transferred to the bulb easily. Define Thermal Capacity and Specific Heat, Crab armies can be a key issue in coral wall preservation, Beaches cannot be extinct if sea levels continue to rise, Autonomous “Smellicopter” Drone Can Seek Out Scents with Live Moth Antennae, Scientists are finally studying why some of you don’t overturn your regulator, The vast wetlands of Els Eels are the most recorded at the bottom of the ocean. Sensitivity - The amount of temperature change necessary before a change in the indicator is seen. Sensitivity of a thermometer is the length of increase of the liquid per degree rise in temperature. Hence, their use is limited to areas where only man… 20 The diagram shows a liquid-in-glass thermometer. Range is the converse of sensitivity, i.e., the longer the range, the lower is its sensitivity. Change in bulb volume, 2. More sensitive means more noticeable expansion. Therefore, they must be handled with extra care because they are likely to break. For measuring temperature a sensitive thermometer is needed. Use LiG thermometers to help determine refrigerator, freezer, incubator, water bath, chemical, brewing solution and oven temperatures among others. 17. The properties you really want to know about are range and resolution. Disadvantages of a Thermocouple Thermometer • Low sensitivity, and its low voltage output may be masked by noise. Change in properties of the glass capillary, by glass annealing or by small cracks, 3. How many kinds of fixed points in thermometer scale? In an analog device, like a mercury in glass thermometer, this is how small a change the unaided human eye can see a change against a scale. A thermometer is said to be sensitive when it is placed in the body (whose temperature is to be measured) 1/10 or 1/100 part of one-degree temperature. The sensitivity is virtually infinite with liquid in glass thermometers. Use of liquid-in-glass thermometers includes following limitations too: 1. Mercury was the liquid the most often used because of its good reaction time, repeatability, linear coefficient of expansion and large temperature range. If you put such a thermometer into boiling water, it sort of explodes as the expanding fluid shatters the glass casing. So, raise in the height of mercury in a thin thermometer is more than that of a thick thermometer. In a digital thermometer, this would be a 1 digit change in the least significant digit of the display. They can not be applied in regions where highly accurate results are desirable. Post navigation ← 15. The range of a thermometer, on the other hand, refers to the dissimilarity between the maximum and the minimum temperature. The sensitivity depends on the reversible thermal expansion of the liquid compared to the glass. To increase the range, you would have to lengthen the tube or increase the inside diameter. The sensitivity of a thermometer is defined as the increase in the length of the mercury column per unit increase in temperature. A:. Too much liquid, however, would cause the thermometer to react very slow to temperature changes, as the heating of the liquid will take longer and the liquid will take longer to adapt to the outside temperatures t… So number 4, longer bore, lets you increase the range of the thermometer. Course overview. Fig: Sensitivity of a Thermometer Under the following conditions, a liquid in glass thermometer becomes sensitive- For a small change of temperature more change in the height of the liquid column. Liquid-in-Glass Thermometers Let’s start our story with one of the most common thermometers used today, the liquid-in-glass (LiG) thermometer. These cookies do not store any personal information. As the temperature of the liquid in the reservoir increases, it expands and rises into the capillary tube. A LiG thermometer, by definition, is a glass capillary tube with a liquid-filled bulb at one end. For a small change of temperature more change in the height of the liquid column. Organic liquids which are usually employed for construction of liquid-in-glass thermometers include toluene, ethyl alcohol and pentane. The liquid must have the following properties: Be able to be seen easily There are two major types of Liquid-in-glass thermometers which are mentioned below: . The range can be increased by lengthening the bore. The sensitivity and responsiveness can be increased by making the bulb at the bottom smaller and decrease the amount of glass surrounding it. Sensitivity vs Range Hi! The sensitivity of a thermometer refers to the minor temperature transform that can be detected or considered. A mass of liquid and diameter of liquid thread B mass of liquid and length of stem C thickness of glass bulb and diameter of liquid thread I guess what you have mentioned here is that the range is dependent on how much liquid you have and far you allow that liquid to expand within your thermometer. Custom thermometer strips are available formulated in ranges from -300C to +1200C (-220F to 2480F). (b) The highest temperature that this thermometer can measure is 110 °C. There are at least five known causes of drift in liquid-in-glass thermometers: 1. For this reason, liquid thermometers have a reservoirto increase the amount of liquid in the thermometer. Sensitivity of a thermometer is the length of increase of the liquid per degree rise in temperature. A glass bulb with thinner wall – Heat can be transferred to the bulb straightforwardly. Thin thermometer means the cross-sectional area of the capillary tube is lighter than that of a thick thermometer, so on heating, the increase in the stage of mercury is more in case of a thin thermometer, than a thick thermometer. State the lowest temperature that it can measure. The principle used to measure temperature is that of the apparent thermal expansion of the liquid. Sensitivity, range and linearity of measuring instruments 17. You also have the option to opt-out of these cookies. Post navigation ← 14. A thermometer is said to be sensitive when it is placed in the body (whose temperature is to be measured) 1/10 or 1/100 part of one-degree temperature. A typical liquid-in-glass thermometer is shown in the figure below. Necessary cookies are absolutely essential for the website to function properly. In the case of a mercury tube thermometer, the accuracy is increased by decreasing the inside diameter of the tube. Liquid-in-glass thermometers measure the thermal expansion of a liquid, which is placed in a solid container, on a length scale. GCSE Keywords: Scale, Linear, Precision, Sensitivity. All rights reserved. The greater the fluid expansion, the more sensitive the thermometer. It is calculated in meter/degree Celsius. We'll assume you're ok with this, but you can opt-out if you wish. (1) sensitivity by increasing bulb size (& hence the thermometric liquid) OR by reducing bore diameter (2) responsiveness (and its not "responsitivity") by reducing bulb size OR reducing thickness of the glass used to make the bulb Alcohol is also used with this type of instrument. –10 0 10 20 30 40 50 60 70 80 90 100 110 °C liquid thread glass bulb stem liquid tube How can the thermometer be made more sensitive? These cookies will be stored in your browser only with your consent. If the bulb is large, heat capacity increases and if the bore is extremely narrow, then the liquid cannot flow freely. 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