A thermometer is a device that measures temperature. Alcohol-based and Mercury-based thermomoters measure temperature on either the degress Celcius (°C) scale or the degrees Fahrenheit (°F) scale. Alcohol and Mercury thermometers function in a similar way. A liquid (mercury or alcohol) is contained in a glass bulb which is connected to a capillary and the end is sealed with an expansion bulb. As temperature increases, the volume of liquid expands and the meniscus moves up the capillary. The position of the meniscus shows the temperature against the inscribed scale. The bulb thermometer can be easily miss-read; be sure to interpret the value/units reading “up” the thermometer (to avoid mistaking seventy-five degrees for eighty-five degree).

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