# hw2_solution - ECE 440 Homework 2 Solution Due: Friday,...

This preview shows pages 1–2. Sign up to view the full content.

ECE 440 Homework 2 Solution Fall 2009 Due: Friday, September 11, 2009 1. Gold, one of the best conductors, has a face-centered cubic lattice. The lattice constant is 4.08Å. The force holding the lattice together is the metallic bonding, i.e. an interaction between positive ion cores and surrounding free electrons in the so-called electron sea. Assume that each gold atom contributes one electron to the electron sea. Determine the free electron density in gold, and compare that to the electron density of intrinsic silicon, which is 1.5x10 10 /cm 3 . Answer: We can compute using what we know about FCC: 3 22 3 0 10 9 . 5 1 * 08 . 4 * ) 4 ( cm e atom electron A cell unit cell unit atoms n e × = = Or using the properties of gold that we know: m V n atom a e ρ = = Where: mole atoms number Avogadro atoms per electrons of number m Kg mole gram Mass Atomic m a atoms 23 3 3 10 022 . 6 1 10 3 . 19 7 . 196 × = = = = × = = = 3 22 23 3 3 10 9 . 5 197 . 0

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 10/14/2009 for the course ECE 440 taught by Professor Lie during the Fall '09 term at University of Illinois at Urbana–Champaign.

### Page1 / 3

hw2_solution - ECE 440 Homework 2 Solution Due: Friday,...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online