What is the main energy conversion that occurs when you plug in a lamp

Electric energy conservation which converts into heat and light

Explanation:

The transformation of energy  from one form energy into another form, and throughout this conversion, the energy that we give to a device will comes out. However, the energy that is given may or may not coming out in the required form.

For example, we plug in a lump means we give an electrical energy into a lamp and the lamp produces light,  but we also get heat energy from the lamp(it is the  form of energy which is undesirable coming from a lamp).