ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY
Thermometers. Digital (top) and liquid thermometers. Digital thermometers most commonly use thermistors, resistors which vary according to temperature, to measure temperature. Liquid thermometers have a bulb of liquid, often mercury. If this is warmed it expands, causing liquid to rise up a thin internal tube which is calibrated to show temperature.
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