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Bài giảng "Vật liệu học - Chương 6: Electrical properties" cung cấp cho người học các kiến thức về Ohm’s law, energy levels of an isolated atom, conduction & electron transport, charge carriers in insulators and semiconductors, energy bands, the mass action law,. . | Bài giảng Vật liệu học - Chương 6: Electrical properties Chapter 6 Electrical properties Ohm’s law 1 CuuDuongThanCong.com https://fb.com/tailieudientucntt • Ohm's Law: V=IR voltage drop (volts = J/C) resistance (Ohms) C = Coulomb current (amps = C/s) • Resistivity, : -- a material property that is independent of sample size and geometry surface area RA of current flow l current flow path length • Conductivity, 1 2 CuuDuongThanCong.com https://fb.com/tailieudientucntt Which will have the greater resistance? 2 2 8 D R1 D 2 D 2 2 R1 2D R2 2D D 2 2 8 2 Analogous to flow of water in a pipe Resistance depends on sample geometry and size. 3 CuuDuongThanCong.com https://fb.com/tailieudientucntt Further definitions J= E 5 CuuDuongThanCong.com https://fb.com/tailieudientucntt 6 CuuDuongThanCong.com https://fb.com/tailieudientucntt 7 CuuDuongThanCong.com https://fb.com/tailieudientucntt CONDUCTIVITY: COMPARISON • Room temperature values (Ohm-m)-1 = ( m)-1= S m-1 METALS conductors CERAMICS -10 Silver 6.8 x 10 7 Soda-lime glass 10 -10-11 Copper 6.0 x 10 7 Concrete 10 -9 Iron 1.0 x 10 7 Aluminum oxide 9 CuuDuongThanCong.com https://fb.com/tailieudientucntt EXAMPLE: What is the minimum diameter (D) of the wire so that V < 1.5 V? ( =6.07 x 107 (Ohm-m)-1) 100 m Cu wire - I = 2.5 A + V 100 m < 1.5 V V R 2.5 A D 2 A I 4 6.07 x 107 (Ohm-m)-1 Solve to get D > 1.87 mm 10 CuuDuongThanCong.com https://fb.com/tailieudientucntt Energy levels of an isolated atom 11 CuuDuongThanCong.com https://fb.com/tailieudientucntt 12 CuuDuongThanCong.com https://fb.com/tailieudientucntt 13 CuuDuongThanCong.com https://fb.com/tailieudientucntt ELECTRON ENERGY BAND STRUCTURES 14 CuuDuongThanCong.com https://fb.com/tailieudientucntt BAND STRUCTURE .