Bimetallic strip thermometers are comprised of two fused pieces of different metals that expand at different rates when heated. A pointing device is attached to the pieces of metal, and when the metals are heated, one piece expands faster than the other, causing the metal combination to bend and allowing the pointing device to move up or down a scale of degrees. When the metals cool, they move back to their original shape, allowing the pointing device to also move back down the scale.
There are benefits and drawbacks of using a bimetallic strip thermometer, depending on the function needed. They are generally cheap and easily to get. They are durable, making them long lasting and simple to use for multiple purposes. They are easily calibrated, making them more versatile than other thermometers. However, they have a fairly slow response time. Although calibration is simple, the bimetallic strip thermometer does require frequent recalibration for accurate readings.
A variation of the bimetallic strip thermometer can also be used with a coil system, such as what is seen with thermostats for homes and vehicles. These variations of bimetallic strip thermometers are more sensitive to smaller temperature changes, making them ideal for these particular functions.