7-HW Solutions

7-HW Solutions - HW#7: Solid State Phys320 Spring 2007...

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Unformatted text preview: HW#7: Solid State Phys320 Spring 2007 (Reshchikov) p. 1 Problem 1 Using "unit analysis", find the total number N of Cu atoms (M = 63.55 g/mole, = 8.96 g/cm 3 ) in a Cu wire of length 200 m and diameter of 0.1 mm. Assuming that each atom of Cu provides one free electron, find the concentration of free electrons in this wire? ( ) ( ) 2 2 3 23 22 3 3 22 3 3 23 22-3 d 3.14 (0.01 cm) V= 20000 cm = 1.57 cm 4 4 8.96 g mole 6.022 10 atoms 8.4910 atoms/cm 63.55 g mole cm 8.4910 atoms/cm 1.57 cm 1.3310 atoms 8.4910 cm A a a e a L N n M N n V n n = = = = = = = = = Problem 2 Find the drift velocity and time for an average electron to travel through the Cu wire of Problem 1 if the current is 0.1A? ( ) ( ) 2 2 2 2 22 3 19 5 0.1 A , where 1273 A/cm 3.14 (0.005 cm) 1273 A/cm 0.0937 cm/s 8.49 10 cm 1.6 10 x 20000 cm 2.13 10 s or 60 hours 0.0937 cm/s d d d j I v j ne r v C t v = = = = = = = = = Problem 3 Draw simple band diagrams with appropriate labels (axes, E F , E A , E D , E C , E V ) and roughly to scale for a) Cu; b) n-type...
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This homework help was uploaded on 04/22/2008 for the course PHYS 320 taught by Professor Baski during the Spring '04 term at VCU.

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7-HW Solutions - HW#7: Solid State Phys320 Spring 2007...

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