Here you can find the meaning of In an n-p-n transistor, the majority carriers in the emitter and collector are :a)Free holesb)free electronsc)Free ionsd)Valence electronsCorrect answer is option 'B'. The maximum possible electrons in an orbit is This is the case of well separated or isolated atoms.Q. Obviously, some p-electron states are empty. So, out of the 4N electrons, 2N electrons are in the 2N s-states (orbital quantum number l = 0) and 2N electrons are in the available 6N p-states. The maximum possible number of outer electrons in the orbit is 8 (2s + 6p electrons). Hence, the total number of outer electrons in the crystal is 4N. The number of electrons in the outermost orbit is 4 (2s and 2p electrons). For Si, the outermost orbit is the third orbit (n = 3), while for Ge it is the fourth orbit (n = 4). Therefore, for understanding electron energies in Si or Ge crystal, we need to consider the changes in the energies of the electrons in the outermost orbit only. The overlap (or interaction) will be more felt by the electrons in the outermost orbit while the inner orbit or core electron energies may remain unaffected. However, in a crystal, the atoms are close to each other (2 Å to 3 Å) and therefore the electrons interact with each other and also with the neighbouring atomic cores. The electron energy will be same if all the atoms are isolated, i.e., separated from each other by a large distance. Electrons of each atom will have discrete energies in different orbits.

Read the following text and answer the following questions on the basis of the same:Band theory of solid:Consider that the Si or Ge crystal contains N atoms.

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