Solids expand on heating can be shown by two different experiments.
The experiments are :
Experiment A : An iron bar is taken and its length measured accurately. The iron bar is then slowly heated for a certain period of time & measured accurately [with a vernier calipers or otherwise]
Observation : It is observed that the iron bar has increased in length on heating.
Experiment B : A simple ball & ring apparatus is taken, which consists of a metal ball which can just pass through the circular metal ring. The metal ball is then heated for a certain period of time.
Observation : After heating, the metal ball does not pass through the ring, since on heating it has expanded in size and hence cannot pass through the ring.
Conclusion : All solids expand on heating.
