Homework 2-solutions

# Homework 2-solutions - wolf (bw7658) Homework 2 Sutcliffe...

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Unformatted text preview: wolf (bw7658) Homework 2 Sutcliffe (50965) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. This assignment covers the remaining ma- terial that will be in the first exam. 001 10.0 points You are caught in a radar trap and hope to show that the speed measured by the radar gun is in error due to the uncertainty prin- ciple. If you assume that the uncertainty in your position is large, say about 10 m, and that the car has a mass of 2150 kg, what is the uncertainty in the velocity? 1. 2 . 5 10- 39 m / s correct 2. 4 10 38 m / s 3. 1 10- 39 m / s 4. 5 . 10- 38 m / s 5. 1 10 33 m Explanation: x = 10 m m = 2150 kg v = h 2 m x = 1 . 055 10- 34 J s 2 (2150 kg) (10 m) = 2 . 45349 10- 39 m / s 002 10.0 points In a one-dimensional particle in a box, for n = 7, how many WHOLE wavelengths equals the size of the box? 1. 7 2. 3.5 correct 3. 6 4. 14 Explanation: For n = 7 the wavefunction would be x = 0 x = L 003 10.0 points An electron is confined in a 1-dimensional box 3 nm long. Calculate the energy required for it to move from the n = 8 to the n = 9 energy level. 1. 3 . 414 10- 28 J 2. 2 . 133 10- 14 J 3. 1 . 138 10- 19 J correct 4. 6 . 694 10- 21 J 5. 5 . 238 10- 19 J 6. 1 . 717 10- 14 J 7. 2 . 133 10- 19 J Explanation: n 1 = 8 n 2 = 9 h = 6 . 626 10- 34 J s L = 13 10- 9 m m = 9 . 109 10- 31 kg E = E n 2- E n 1 = ( n 2 2- n 2 1 ) h 2 8 mL 2 = (9 2- 8 2 ) (6 . 626 10- 34 J s) 2 8 (9 . 109 10- 31 kg) (3 10- 9 m) 2 = 1 . 13802 10- 19 J 004 10.0 points A quantum mechanical particle in a box in its ground state is most likely to be found 1. in the middle of the box. correct 2. is equally likely to be found at all positions in the box. wolf (bw7658) Homework 2 Sutcliffe (50965) 2 3. is equally likely to be found at all positions except the very center of the box. 4. at the very edge of the box. 5. at both edges of the box. Explanation: The ground state is 1 which has maximum probability in the middle of the box. 005 10.0 points For n = 7 and = 4, what is m ? 1. 9 2.- 4,- 3,- 2,- 1, 0, +1, +2, +3, +4 correct 3. 0, 1, 2, 3 4. 0, 1, 2, 3, 4 5. 18 Explanation: 006 10.0 points Which of the following sets of quantum num- bers is allowed for an atomic orbital?...
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## This note was uploaded on 03/09/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas at Austin.

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Homework 2-solutions - wolf (bw7658) Homework 2 Sutcliffe...

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