Electrical properties of Engineering Materials and its application

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1. Resistance Voltage Current Conductance

2. 1. Due to motion of electrons 2. Depends upon number of free electrons 3. Arrangement of electron state 4. Electron energy states 5. Mostly responsible for electrical conductivity of conductors and semi-conductors Due to motion of ions

3. METALS Cu Mg INSULATOR SEMICONDUCTOR Conduction band Valence band

4. Free Electrons 1.Electrons participating in conduction process 2. Valance electrons that jump to conduction 3. Above the Fermi Energy 4. Loose and Nucleus doesn’t bind it 5. Free electron jumping from valance band to conduction band leave behind a hole 6. Hole moves in direction opposite to electron movement 7. Positively charged & same magnitude as electron

5. Drift Velocity Electric field Conductivity Number of free electrons

6. Electric conduction based on inherent electronic structure eg . Si (1.1eV) Ge (0.7eV), GaAs , InSb , CdS , ZnTe Electric conduction dictated by impurity atoms

7. Terms for Holes

8. Si/ Ge (Gr14) doped with P/As (Gr15) 4 Valance electrons 5 Valance electrons

9. Si/ Ge (Gr14) doped with B/Al/ Ga (Gr13) 4 Valance electrons 3 Valance electrons

10. Capacitance Capacitance when vacuum between plates Capacitance when dielectric material is used Dielectric constant Permittivity of free space Permittivity of DM

11. Surface Charge Density Vacuum DM

12. Polarization: total dipole moment per unit volume

13. Free Energy

14. SONAR

15. ACTUATOR