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Electrical Engineering Materials

EE 3219. Electrical Engineering Materials. Dr. Md. Sherajul Islam Associate Professor. Department of Electrical and Electronics Engineering Khulna University of Engineering & Technology Khulna, Bangladesh. LECTURE - 3. Electrical and thermal conduction in solids.

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Electrical Engineering Materials

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  1. EE 3219 Electrical Engineering Materials Dr. Md. Sherajul Islam Associate Professor Department of Electrical and Electronics Engineering Khulna University of Engineering & Technology Khulna, Bangladesh

  2. LECTURE - 3 Electrical and thermal conduction in solids

  3. Resistivity of non pure metals

  4. Resistivity of non pure metals Potential energy of the electron changes as it approaches the impurity

  5. Resistivity of non pure metals

  6. Matthiessen's Rule An empirical rule which states that the total resistivity of a crystalline metallic specimen is the sum of the resistivity due to thermal agitation of the metal ions of the lattice and the resistivity due to the presence of imperfections in the crystal.

  7. Resistivity of non pure metals There may also be electrons scattering from dislocations and other crystal defects,as well as from grain boundaries

  8. Resistivity of non pure metals

  9. Resistivity of non pure metals

  10. Resistivity of non pure metals

  11. Resistivity of non pure metals

  12. Resistivity of non pure metals

  13. Thermal Conductivity Thermal conduction in a metal involves transferring energy from the hot region to the cold region by conduction electrons. More energetic electrons (shown with longer velocity vectors) from the hotter regions arrive at cooler regions, collide with lattice vibrations, and transfer their energy. Lengths of arrowed lines on atoms represent the magnitudes of atomic vibrations.

  14. Thermal Conductivity

  15. Thermal Conductivity Heat flow in a metal rod heated at one end . Consider the rate of heat flow, dQ/dt, cross a thin section δx of the rod. The rate of heat flow is proportional to the temperature gradient δT/ δx and the cross-sectional area A.

  16. Thermal Conductivity Fourier's law. The law of heat conduction, also known as Fourier's law, states that the time rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area, at right angles to that gradient, through which the heat flows.

  17. Thermal Conductivity Wiedemann-Franz-Lorenz law

  18. Thermal Resistance

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