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Project on atomic model and history:            Atom is the smallest constituent unit of ordinary matter that constituent of chemical elements viz electron, proton, neutron. Atoms are extremely small, typical sizes are around 100 picometers. In 1800 AD Jhon Dalton use the concept of atom to explain why chemical elements seemed to combine in ratios of small whole numbers. And Dalton give the atomic theory famous as "Dalton's atomic theory". Atom is mainly consist of two main part as nucleus and electron shell. The nucleus is made of proton and neutron. Proton is positively charged and neutron has no charge i.e neutral. And electron is negatively charge. diagram of electron and proton Discovery of Electron:      In 1897, J J Thomson  discovered that cathode rays are not electromagnetic waves but are made of particles taht are 1800 times lighter than hydrogen (the lightest atom). And that particle are electron and it is negatively charged. ...

Project Report on semiconductors:- INTRODUCTION:          Most of the solids can be define into three classes: 1) conductor 2) insulator and  3) semiconductor (1)  conductor : those solids can be called as conductor who have good electric conductivity property. Conductivity define by the presence of free electron. That means conductor have free electron by which it can easily conduct current. Example:- copper, iron etc. (2)  insulator :     those solid can be called insulator who have no electric conductivity. That means insulator have no free electron and hence they cannot conduct current. Example:- wood, glass etc. (3)  semiconductor :   semiconductor are those solid whose electric conductivity is between conductor and insulator. Semiconductor can conduct current in some particular conditions.    Theory:-             The energy band structure of the semiconductors is simi...