NEETPhysicsThermal Properties of Matter
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R . Assertion A : When a rod lying freely is heated, no thermal stress is developed in it. Reason R : On heating, the length of the rod increases. In the light of the above statements, choose the correct answer from the options given below:
Options
- ABoth A and R are true and R is the correct explanation of A
- BA is false but R is true
- CBoth A and R are true but R is NOT the correct explanation of A
- DA is true but R is false
Correct answer
C. Both A and R are true but R is NOT the correct explanation of A
Step-by-step solution
Thermal stress is mechanical stress created by any change in temperature of a material. When the body is under some constraints, thermal stress is generated. But if it is lying freely, no thermal stress is developed. The increase in length of a body with temperature is given by ∆ L = L α ∆ T So, with the increase in temperature, the length of the rod increases. A and R are true but R is not the correct explanation of A .