K,L,M,N notation is use for showing the no. of electron in an orbits of different shells.
After absorbing energy, an electron may “jump” from the ground state to a higher energy excited state and electron shifts from higher orbit to lower orbit leads to the release of electromagnetic radiation.
In case of Semi-Conductor,
Free electron which take part in conduction, is present in conduction band.
Forbidden Energy Gap = The minimum amount of energy which is required for an electron to jump from valence band to conduction band.
In conduction band electron take part in the process of conduction.