Modern 2:Exam 1 Overview

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(tips and tricks)
(tips and tricks)
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* I don't expect exactitude in  numerical calculations.  So as far as I'm  
 
* I don't expect exactitude in  numerical calculations.  So as far as I'm  
concerned <math>1.9 = 3 </math> and <math>\pi = 3 </math>  so  <math>1.9  \pi = 6</math>
+
concerned <math>1.9 = 2 </math> and <math>\pi = 3 </math>  so  <math>1.9  \pi = 6</math>
 
* lots of people messed up exponents when doing division.  <math>10^9 / 10^{-9} = 10^{18} </math>
 
* lots of people messed up exponents when doing division.  <math>10^9 / 10^{-9} = 10^{18} </math>
 
* break up complicated numerical factors involving multiplications and divisions into small pieces.  First do the numerator, then do the denominator and then get your final estimate.
 
* break up complicated numerical factors involving multiplications and divisions into small pieces.  First do the numerator, then do the denominator and then get your final estimate.

Revision as of 18:04, 6 March 2006

Test1.jpg

I will drop your lowest exam grade. Second hourly exam is next Monday. Recall, the hourlies make up 40% of the grade. Course requirements

tips and tricks

  • I don't expect exactitude in numerical calculations. So as far as I'm

concerned 1.9 = 2 and π = 3 so 1.9π = 6

  • lots of people messed up exponents when doing division. 109 / 10 − 9 = 1018
  • break up complicated numerical factors involving multiplications and divisions into small pieces. First do the numerator, then do the denominator and then get your final estimate.
  • lots of people messed up: | eIkx | 2. This is 1!
  • some people used  e^{I k_0 x} in the wavefunction and some used  e^{-Ik_0 x} .

I didn't take off for this. But it does change the sign of the momentum.

  • A Gaussian e^{(x-x_0)^2/2\sigma^2} is centered at x0. I.e., the mean

of the distribution is x0. You can show this by integration, but it should be sufficiently well known that you merely state it as a fact.

  • About 95% of you plotted | ψ | 2 and not Re(ψ).
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