Why electrical loose connections generate heat?

Here is my video answer:

Loose connectors create a high resistance to electrical current flow. This means that there is resistance to the electric current flow causing power to be dissipated as heat. You should get the wall outlet fixed because it could cause a fire. However, I was surprised that the cord is getting hot. If it is getting hot evenly along its length it is not the socket at fault. You should use networking equipments that are of good quality.