Question

what is a bimetallic strip ? why does it bend on heating ? describe any two uses of bimetallic strip.​

Answer 1

in a bimetallic strip the one metal one man has a high thermal expansion of its length another one has less thermal expansion that's why one one expands faster than other one and bimetallic strips are getting bended.
hope it helps

Answer 2

Bimetallic Strip

A bimetallic strip consists of two different materials with different expansion coefficients that are bonded together. For example, for brass and steel, the coefficients of linear expansion are:

Brass: 19 x 10^-6 /°C       Steel: 11 x 10^-6 /°C

When this bimetallic strip is heated, the brass expands more than the steel and the strip curves with the brass on the outside. If the strip is cooled, it curves with the steel on the outside.

Bimetallic strips are used as switches in thermostats. 

bi-metalic strips bend when heated Two metals making up the strip have different rates of expansion, so as heat is applied and the metals expand, one metal will expand faster than the other, causing that side to grow longer faster than the other side. Since the faster growing metal strip is bonded to the slower expanding, now shorter piece of metal, some movement must occur and the only means of movement is to bend.

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. The strips are joined together throughout their length by riveting, brazing 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. The metal with the higher is on the outer side of the curve when the strip is heated and on the inner side when cooled.