Why is invar often used to make accurate technical instruments that are in hot situations?

Invar is an alloy of iron and nickel that has a very low coefficient of thermal expansion. This means that it expands very little when heated, making it ideal for use in instruments that need to be accurate even in hot conditions.

Invar is used in a wide variety of applications, including:

* Measuring tapes and surveying instruments

* Thermometers and other scientific instruments

* Pendulums and other timing devices

* Thermostat and other control devices

* Invar is also used in some medical devices, such as pacemakers and artificial joints.

Invar is a valuable material for any application where accuracy is important, even in hot conditions. Its low coefficient of thermal expansion makes it ideal for use in instruments that need to be precise, even in the most extreme temperatures.