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Bimetal strips — also known as bimetallic strips — are used in electronics and thermal engineering as a means of transferring thermal energy into mechanical movement. A common application of this technology is in thermostats or heat sensitive switches in which a circuit is either connected or broken when a certain temperature is reached. The strips work by pairing two metals which react to changes in temperature at different rates, causing the two strips to bend in a certain direction in an effect similar to the refraction of a light beam entering a glass block.
Bulb thermometers are good for measuring temperature accurately, but they are harder to use when the goal is to control the temperature. The bimetallic strip thermometer, because it is made of metal, is good at controlling things. The principle behind a bimetallic strip thermometer relies on the fact that different metals expand at different rates as they warm up.
Temperatures can be meassured based on the principle of different thermal expansion of solids. For this purpose, two metal strips e. When heated, the metal strip deforms due to the different degrees of expansion.
Bi-metallic strips are subject to bending due to heat - and can be used to convert change in temperature to mechanical displacement. Bending occurs towards the side of the metal with the lowest temperature coefficient of expansion. Assuming two metals with the same shape joined together - bending of a bi-metal strip due to change in the temperature can be calculated as.
The principle behind a bimetallic strip is that different metals expand to different extents with temperature changes. By combining two different metals one on top of another into a strip, a bimetallic strip is formed. As the two metals expand or contract differently under the same temperature change, the strip bends.
A bimetallic strip is used to convert a temperature change into mechanical displacement. The strip consists of two strips of different metals which expand at different rates as they are heated, usually steel and copperor in some cases steel and brass. The strips are joined together throughout their length by rivetingbrazing or welding. The different expansions force the flat strip to bend one way if heated, and in the opposite direction if cooled below its initial temperature.
Have you ever noticed that there are tiny gaps in rails and flyovers? They are designed that way to prevent the matter from bending or breaking in summer when it expands. Matter always expands, or becomes bigger, when it is heated.