Lecture 22.pdf - Free Electron Model of Metals The metallic state Most elements are metallic More than 2/3 of the periodic table Ductile Malleable Good

Lecture 22.pdf - Free Electron Model of Metals The metallic...

This preview shows page 1 - 11 out of 37 pages.

Free Electron Model of Metals
Image of page 1

Subscribe to view the full document.

The metallic state Most elements are metallic. More than 2/3 of the periodic table Ductile, Malleable Good conductors of heat and electricity Need a theory of metallic state To understand their properties and (to contrast) the properties of the insulators Opaque and look shiny
Image of page 2
Ohm’s law R V I R 1 Conductance We write Ohm’s law in a form that depends only on the property of material E J J Current density (A m -2 ) E Electric field (V m -1 ) Conductivity ( -1 m -1 ) Note A J I l E V A ( l ) = Area (length) of conductor A l A l R = Resistivity of material 1
Image of page 3

Subscribe to view the full document.

Hall Effect + + + + + + + + + + + + - - - - - - - - - - - - - - - - x E x J y E z H x y z e x v z H e x v Electric field in x-direction. Magnetic field in z-direction Electrons experience Lorentz force in -y-direction and accumulate on the side of the specimen. Transverse electric field ( E y ) in generated. Hall coefficient z x y H H j E R
Image of page 4
x T T A dt dQ 1 2 T J dt dQ A 1 Thermal conductivity dx dT J T Thermal current density (Thermal energy per unit time crossing a unit area perpendicular to the hear flow) W/m 2 Thermal conductivity (W/m.K) Fourier’s Law Thermal conductance = l A / Thermal resistance = A l / = length of the conductor l 1 T 2 T A Q x
Image of page 5

Subscribe to view the full document.