Modern 2:Exam 1 Overview

Course Wikis

>

Physics Course Wikis

>

Modern 2

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: | e^Ikx | 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).