Recent content by xWaffle

1. Simple Op-Amp Inverting Amplifier

Homework Statement I need to find an expression for the gain in this circuit. I know it is an interting amplifier, because with the models we were given to look at, this one fits the inverting amlpifier. I've also constructed a simulation in a simple Java applet that I have. My problem...
2. Recommendations for Study Materials [QM]

You guessed it, we're using Griffith's. If you can call it "using." We aren't assigned reading, we aren't assigned problems out of the book. 99% of the time when that happens in a class, you think to yourself, "why do I even need this book, then?" I have purchased all of the books for all of...
3. Recommendations for Study Materials [QM]

Hello all, I'm taking my first actual quantum course this semester. I went over "briefly" some quantum mechanics Fall of 2012 in a Modern Physics course during my sophomore year, currently I'm a junior. To get straight to the point, this course is making me miserable. I had high hopes for...
4. Proving that the Dirac Delta is the limit of Gaussians

Homework Statement I need to prove for arbitrary functions φ(x) that: \lim_{\lambda \to 0} \int_{-\infty}^{\infty} \frac{1}{\sqrt{2 \pi} \lambda} exp\left( \frac{-x^{2}}{2 \lambda^{2}} \right) \varphi(x) dx = \varphi(0), which, in the sense of distributions is basically the delta...
5. Expectation Values - Quantum

Homework Statement \Psi (x) = C e^{i k_{0} x} e^{\frac{-x^{2}}{2 a^{2}}} Find \left\langle x \right\rangle, \left\langle x^{2} \right\rangle, \left\langle p \right\rangle, \left\langle p^{2} \right\rangle. Homework Equations Operators make a "psi-sandwich": \left\langle x \right\rangle =...
6. Length of coaxial cable, based on signal reflection

Thank you, I think I got what I needed from there. It just seemed like too simple of a problem. _____________ Now, would anyone happen to be able to tell me why a signal inverts iitself when coming back down the coaxial cable if we've shorted the other end? I know the math that explains...
7. Length of coaxial cable, based on signal reflection

Homework Statement We measured the time between a signal source, and it's reflection coming back through our probe after going through an open-ended coaxial cable. My teacher told us this: the cable has a polyethylene insulator between central wire and the grounding web, which has a...
8. Prove rotational invariance leads to conservation of ang. momentum

Homework Statement Noether's theorem asserts a connection between invariance principles and conservation laws. In section 7.8 we saw that translational invariance of the Lagrangian implies conservation of total linear momentum. Here you will prove that rotational invariance of L implies...
9. Power Series to solve Second order Differential Equations

It's an assignment, I'm much more than capable of solving this with more traditional means, but I can't submit that work. I don't have my notebook at the moment but from memory, when using power series, you assume y = \sum_{n=0}^{\infty} a_{n}x^{n} Which means y' =...
10. Power Series to solve Second order Differential Equations

Homework Statement When solving a D.E. with power series, I've encountered something along the lines of: (2 - r)^{2}g'' = -2 Homework Equations Power Series The Attempt at a Solution I know I am just supposed to assume such a series exists, and work from there. But I'm really...
11. Help with Maclaurin series of (1/x), (1/x^2), etc

Maybe I'm jumbling up notation.. The value I was calling x0 is where the function is a minimum value, and then I need to approximate the function for when |x - x0| is <<< than x0 I was assuming I needed to use some sort of series because it's included in the "series" part of the assignment
12. Help with Maclaurin series of (1/x), (1/x^2), etc

But how am I supposed to find this value of x-zero to use in the series? I thought I had to use the series to find it. Or do I take its limit as it approaches zero, or..? I'm still lost
13. Help with Maclaurin series of (1/x), (1/x^2), etc

Homework Statement I have the equation f(x) = \frac{\lambda^{2}}{ax^{2}}-\frac{\gamma ab}{x} What I am assigned to do is find a value of x at it's smallest, then approximate the value of the function when x - x(smallest) is much much greater than x(smallest). Homework Equations f(x) = f(0)...
14. Wavelength of Particle Passing Through Potential Barriers

Homework Statement Compare the wavelengths of a particle when it passes a barrier of height (a) +V0 and (b) -V0 where E > |V0|. Calculate the momentum and kinetic energy for both cases. Homework Equations (see below) The Attempt at a Solution I know the wavelength changes in the...
15. Wavelengths of Particle passing Potential Barriers

Homework Statement Compare the wavelengths of a particle when it passes a barrier of height (a) +V0 and (b) -V0 where E > |V0|. Calculate the momentum and kinetic energy for both cases. Homework Equations (see below) The Attempt at a Solution I know the wavelength changes in the...