Question

expansion of a steel rod on heating​

Answer 1

Answer:

first take fire and heat the rod

Answer 2

Answer:

first you ,Rest the iron rod on the two supports  Prevent the rod from moving at one end by placing the kilogram mass on it. Let the other end roll on the needle resting on a small piece of glass (e.g. a microscope slide) placed on the block. Pierce the straw with the needle so that it acts as a pointer.

Heat the rod by moving a Bunsen flame along it. The straw will move with the rolling needle as the rod expands. The movement of the rod cannot be seen, but the magnification of this movement by the straw is impressive.