1M03 2009 ASSIGNMENT 3-3 ¿¯

1M03 2009 ASSIGNMENT 3-3...

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View Results Name: SOO NAM Attempt: 3 / 3 Out of: 28 Started: February 22, 2009 6:51am Finished: February 22, 2009 7:30am Time spent: 38 min. 45 sec. Question 1 (1 point) Consider a metal that has an electrical conductivity of 7.6 x 10 7 ( Ω -m) -1 . It is drawn into a wire 1.8 mm in diameter and 7.0 m long. Calculate the current (in A) if the potential drop across the ends of the wire is 0.072 V. Use decimal notation, digits after decimal: 1 Student response: 2.0 A Correct answer: 2.0 A General feedback: This problem can be solved using an extension of Ohm's Law. For more information, see pages 612- 613 in the text. Equation 18.3 should be particularly useful. Score: 1 / 1 Question 2 (1 point) The typical electrical conductivity value/range for insulators is: Student response: Correct Response Student Response Answer Choices a. 10 7 ( Ω -m) -1 b. 10 -20 to 10 -10 ( Ω -m) -1 c. 10 -6 to 10 4 ( Ω -m) -1 General feedback: Insulators typically have electrical conductivities in the range of 10 -20 to 10 -10 ( Ω -m) -1 . See pg 614 in the text. Score: 1 / 1 Question 3 (1 point) For nonmetallic materials, which of the following is true? Student response: Correct Response Student Response Answer Choices a. The wider the band gap, the lower the electrical conductivity at a given temperature. b. The wider the band gap, the higher the electrical conductivity at a given temperature. General feedback: The wider the band gap, the lower the electrical conductivity at a given temperature. See page 618 of the text for more information. Score: 1 / 1 Question 4 (1 point) An n -type semiconductor is known to have an electron concentration of 5.06 x 10 19 m -3 . If the electron drift velocity is 102 m/s in an electric field of 406 V/m, calculate the conductivity of the material [in (Ohm-m)^-1]. Note: Enter the units precisely as they have been given above. Use decimal notation, digits after decimal: 2
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Student response: 2.04 (Ohm-m)^-1 Correct answer: 2.03 (Ohm-m)^-1 General feedback: The equation for the electrical conductivity of an n -type semiconductor is given on page 626 of the text. The electron mobility may be found using equation 18.7 on page 619. Score:
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1M03 2009 ASSIGNMENT 3-3...

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