Concept of Apparent Expansion:

When a liquid is filled in a container and heated, due to rise in temperature, it expands. Liquid always expands more than solid, so if it is completely filled in container, some liquid will overflow. But due to expansion of container, the whole expansion volume of the liquid will not overflow. This is called apparent expansion of the liquid with respect to container. This concept helps in solving numerical problems based on this concept. To understand how to quickly solve such numerical problems, watch the below given video.

https://youtu.be/-8EIN5_u5v0

Tension in a Clamped Wire:

When a metal wire is clamped between two rigid supports in almost taut state without any tension, on raising the temperature, it expands and a sag is developed in the wire. If temperature is decreased, it tends to contract, but as clamps are rigid, it elastically expands to compensate the thermal contraction which develops a tension in the wire. To understand the concept, watch the below given video.

https://youtu.be/i7Lx19UdFW8