Engineering Physics

Today's easy life is only possible by the development of new materials and their applications. Hence their internal structure is of utmost importance so that the criticalities in achieving various applications of the material can defined clearly. Chapter-I deals with the crystal structure of these materials. Crystallography is the study of internal structure of crystals, their properties, and external or internal symmetries of crystals. We have discussed here nomenclature of crystals and their formation as solids by bondings. Although crystal structure is considered as a perfect arrangement of atoms but in normal practice it is not so as verified by different methods. Point defects are specially being discussed both qualitatively and quantitatively. Finally some idea has been given on the elementary particles of material. The chapter-II is all about quantum physics. Quantum physics completely changed the understandings related to every phenomenon especially in the atomic scale. The atomic behavior is totally different what we are observing as per our human intuition normally applicable to the larger objects. Only quantum physics can be able to explain so many phenomena otherwise unexplained by classical physics. Here the blackbody radiation law is explained using quantum hypothesis including others. Also dual nature of any particle and the introduction of Schrodinger equation are thoroughly discussed. Metal is the most important form of solid. The valence shell electrons of metals are responsible for overall behaviour of metal. In chapter-III we discussed about the free electron theory of metals. Using classical physics some features of metals are not explicable. Modifications in the classical theory have been made by applying quantum mechanics successfully in those cases. Thermionic emission process is quantitatively discussed with quantum statistics. The understanding of semiconductor materials requires different approach other than metals. The electrons in solid crystalline materials are under the influence of a periodic electric field produced by regularly placed ions at their lattice sites of the crystal. Chapter-IV deals with semiconductors. Kronig-Penney model has given quantum mechanical visualization of transfer of electrons from one energy level to an empty energy level by surpassing the forbidden gap and thus explains the properties of metals, insulators and semiconductors. The Hall effect is also discussed as an characterization tool. Chapter-V tells us about photoconductivity and photovoltaics. Any photosensor is basically developed on the basis of the interaction of light (or photons) with the materials. In any semiconductor based detectors the carriers are first created inside the material on its exposure to incident light of proper frequency. These carriers then move around or multiplied by externally controlled processes and finally collected at the ends of the material to form an output electrical signal. The photoconductors and photovoltaic cells are discussed in details. In chapter-VI we have learnt about the different types of magnetic materials. The magnetic materials have been classified into various categories depending on the behavior of material with respect of applied magnetic field. The magnetization factor for various magnetic materials has been described both in qualitative and quantitative way. This helps us to understand the controlling parameter responsible for the origin of magnetization within the material. Superconductivity is one of the most exciting phenomenon in physics. In chapter-VII we have discussed briefly about it. Within a certain critical limits these materials practically shows zero resistivity along with its perfect diamagnetism. First property makes them a potential candidate for carrying electrical power of undiminished strength and the second anti-gravitation or levitation property of a diamagnetic material makes superconductors important for other uses.