Question

Statement (1): When a bimetallic strip made of iron and brass is heated then it bends in the form of concave towards Brass.
Statement (2): The coefficient of linear expansion of iron is less than brass.
(A) Statement (1) and Statement (2) are correct and Statement (2) is correct explanation for Statement (1)
(B) Statement (1) and statement (2) are correct and Statement (2) is not correct explanation for Statement (1)
(C) Statement (1) is true and statement (2) is false
(D) Statement (1) is wrong and statement (2) is true

Answer 1

Hint: In the question two statements are given we have to find out whether the given statements are correct and we have to choose the correct option that explains the statements. The given statements are about thermal expansion.

Complete step by step solution:
The coefficient of linear thermal Expansion is the property of a material which characterizes the ability of a material to expand under the effect of temperature change. It is represented by $\alpha $.
At room temperature $20^\circ C$,
The coefficient of linear expansion of iron is $12 \times {10^{ - 6}}C$
The coefficient of linear expansion of brass is $19 \times {10^{ - 6}}C$
The coefficient of linear expansion of iron is less than the coefficient of linear expansion of brass.
So, statement (2) is correct.
When a material is heated, it expands in length by an amount equal to the product of coefficient of linear thermal expansion and is the change in temperature.
A bimetallic strip consists of two different metals combined together. Those two metals have different coefficients of linear thermal expansion. When a bimetallic strip is heated, the metal which expands the most is one which has the largest coefficient of linear thermal expansion and due to the expansion the metal will bend. The metal with the largest coefficient of linear thermal expansion bends towards the other metal which is having a low coefficient of linear thermal expansion. When a bimetallic strip is cooled from its initial temperature, here the temperature is decreased, so the metal with low coefficient of thermal expansion will bend towards the metal with largest coefficient of linear thermal expansion.
When the bimetallic strip which is made up of iron and brass is heated, the metal with the largest coefficient of linear thermal expansion will bend more i.e. brass will expand more and bends toward the iron. And the iron does not bend in the form of concave towards Brass.
So, the statement (1) is wrong.
Hence the correct answer is option D) Statement (1) is wrong and statement (2) is true.

Note:
The bimetallic strips are commonly used in the appliances which are sensitive to temperature change, even if it is small. The bimetallic strips are used in thermostats, thermometers, clocks, and many more electrical devices.