Types of thermometer Fa-2 Science project

Alcohol thermometer Alcohol thermometer is an alternative to the mercury-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 will evaporate away fairly quickly. An organic liquid is contained in a glass bulb which is connected to a capillary of the same glass and the end is sealed with an expansion bulb. The space above the liquid is a mixture of nitrogen and the vapour of the liquid. For the working temperature range, the meniscus or interface between the liquid is within the capillary. With increasing temperature, the volume of liquid expands and the meniscus moves up the capillary. The position of the meniscus shows the temperature against an inscribed scale. It is an important need for science experiments.

Galileo thermometer Suspended in the liquid inside the cylinder are a number of weights. Commonly those weights are attached to sealed glass bulbs containing colored liquid for aesthetic effect. As the liquid in the cylinder changes temperature, its density changes and the bulbs are free to move – rising or falling to reach a position where their density is either equal to that of the surrounding liquid or where they are brought to a halt by other bulbs. The bulbs differ in density by a very small amount and are ordered such that the least dense is at the top and densest at the bottom so that they form a temperature scale.

Clinical thermometer The traditional thermometer is a glass tube with a bulb at one end containing a liquid which expands in a uniform manner with temperature. The tube itself is narrow (capillary) and has calibration markings along it. The liquid is often mercury, but alcohol thermometers use a colored alcohol. Medically, a maximum thermometer is often used, which indicates the maximum temperature reached even after it is removed from the body. To use the thermometer, the bulb is placed in the location where the temperature is to be measured and left long enough to be certain to reach thermal equilibrium—typically three minutes. Maximum-reading is achieved by means of a constriction in the neck close to the bulb. As the temperature of the bulb rises, the liquid expands up the tube through the constriction. When the temperature falls, the column of liquid breaks at the constriction and cannot return to the bulb, thus remaining stationary in the tube. After reading the value, the thermometer must be reset by repeatedly swinging it sharply to shake the liquid back through the constriction.

Meat thermometer A meat thermometer is a thermometer used to measure the internal temperature of meat, especially roasts and steaks, and other cooked foods. The degree of "doneness" of meat correlates closely with the internal temperature, so that a thermometer reading indicates when it is cooked as desired. Meat should always be cooked so that the interior reaches a temperature sufficient to kill pathogens that may cause foodborne illness; the thermometer helps to ensure this.

Lab thermometer A thermometer (from the Greek θερμός, thermos, meaning "hot" , is a device that measures temperature or temperature gradient using a variety of different principles.[1] A thermometer has two important elements: the temperature sensor (e.g. the bulb on a mercury thermometer) in which some physical change occurs with temperature, plus some means of converting this physical change into a numerical value (e.g. the scale on a mercury thermometer). There are many types and many uses for thermometers, as detailed below in sections of this article.

Thank you ……….. Made by- Riddhi Parihar 7-c