How does a bimetallic strip work?
A traditional thermostat has two pieces of different metals bolted together to form what’s called a bimetallic strip (or bimetal strip). When the strip gets hot, one of the metals expands more than the other so the whole strip bends very slightly. Eventually, it bends so much that it breaks open the circuit.
Which metals are used in bimetallic strip of automatic fire alarm?
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 copper, or in some cases steel and brass.
How can a bimetallic strip be used as a switch?
Bimetallic strips are used in thermostats for measuring and controlling temperature. The strip is connected to a switch and as the temperature changes the strip flexes and opens or closes a contact. They are also used in ovens for measuring temperature.
Where is bimetallic strip used?
The bimetallic strip consists of two different metals having different coefficients of thermal expansion. Bimetallic thermometers are used in residential devices like air conditioners, ovens, and industrial devices like heaters, hot wires, refineries, etc.
What happens when you heat a bimetallic strip?
The bimetallic strips are commonly used in thermostats. It is because the temperature change will bring the mechanical displacement in the metal. When the bimetallic strip is heated, the metal with higher thermal expansion will bend more. Thus they bend towards the metal having a lower thermal expansion.
What does a bimetallic strip consists of?
The strip consists of two strips of different metals which expand at different rates as they are heated, usually steel and copper, or in some cases steel and brass. The strips are joined together throughout their length by riveting, brazing or welding.
What are the three types of thermal expansion?
There are three types of thermal expansion depending on the dimension that undergo change and that are linear expansion, areal expansion and volumetric volume.
What is thermal expansion examples?
The expansion of alcohol in a thermometer is one of many commonly encountered examples of thermal expansion, the change in size or volume of a given mass with temperature. Railroad tracks and bridges, for example, have expansion joints to allow them to freely expand and contract with temperature changes.
What is the fastest mode of transfer of heat?
Radiation
Is the slowest mode of transfer of heat?
The correct option is A) Radiation. Radiation is the fastest mode of heat transfer while conduction is the slowest mode of heat transfer.
Which is faster conduction or convection?
The molecules of a hotter material move faster and therefore have higher kinetic energy than the molecules of a cooler material. Convection can be many times faster than conduction alone. …
Why is convection better than conduction?
In fluids, such as water and air, convection is a much more efficient method of heat transfer than conduction. This difference in efficiency produced the dramatic difference in the time required to melt the ice. Although conduction was at work in both cases, it transferred much less heat than convection.