Search results

  1. A

    Integrating Complex Exponentials

    The integral of a complex exponential ( e^(ix) ) over x from 0 to infinity is supposedly such that the value of the definite integral at the upper limit is zero and so it's just -1/i. Why is this? It's just an oscillating function after all.
  2. A

    Accelerating Wedges with Friction

    1. Homework Statement A block rests on a wedge inclined at an angle \theta. The coefficient of friction between the block and the plane is \mu. Let the wedge move with horizontal acceleration a to the right. Assuming that tan tan(\theta) < \mu, find the minimum value of a for the block to...
  3. A

    Jackson Question

    Can someone explain to me how Jackson, on page 42 of the 3rd ed. of Classical Electrodynamics, when he is deriving the interaction energy W_{int} in his example involving two point charges, gets from equation (1.57) to (1.58). I thought about typing up the TeX but I'm sure most of you have this...
  4. A

    Schools Grad School Selection

    I got accepted to three grad schools: University of Minnesota, Georgia Tech, and NC State. What have you heard about these schools? Which has the best reputation and in which areas of study? I am still flexible in my concentration but I think I'd like to stick with theory rather than experiment.
  5. A

    External Review

    Does anyone know whether it is possible to get one's hands on the external review of a University's physics department? Are they available publicly?
  6. A

    The Proposal for the Neutrino

    A historical question: The neutrino was proposed by Pauli in 1930/31 to solve the crisis caused by the continuous energy distribution of the beta rays (electrons). The neutron was not discovered until 1932. Was Pauli aware, or did he even suspect, at the time of his proposal, the violation of...
  7. A

    Delta Function Difficulties

    1. Homework Statement This is problem 2.46 from Griffith's Electrodynamics. I've already solved the problem but there is one aspect of the solution which bothers me and I can't think of where it is originating. I have found that the potential given in the problem produces an electric field...
  8. A

    Schools Graduate School Statement of Purpose

    I need help with my Statement of Purpose. I have been doing research on experimental high energy particle physics for the past two years of my undergraduate career. However, I have discovered that there is no way I want to continue work in this field in grad school. In my personal statement...
  9. A

    Inductance and Capacitance per Temperature

    I am studying the relationship between transmission speed in a Transmission Cable and the temperature of the cable. This speed is given by (as per discussion in the Feynman lectures) v=\frac{1}{\sqrt{LC}} where L is the inductance per unit length C is the capacitance per unit length...
  10. A

    Graduate Research in Quantum Computation

    What graduate schools are the best if I want to pursue research in Quantum Computation? I know MIT has a good program and I am going to apply there but what other schools would you recommend? I would prefer to stay on this side of the Atlantic.
  11. A

    Temperature Dependence of Dielectric Constants

    Does anyone have information on temperature dependence of dielectric constants? I haven't been able to find anything general enough on Google. I'm particularly interested in Polyethylene, Teflon, and Air but a general description would also be appreciated.
  12. A

    Transmission Line Question

    How is signal transmission speed determined in a transmission line? For example, what determines how long it takes a single pulse to go from one end of a line to the other end. I would assume it depends directly on the conductivity of the material from which the line is made but I'm not sure...
  13. A

    Testing GRE Physics without Quantum Mechanics

    I'm going to be taking the GRE Physics not having taken any formal classes in Quantum Mechanics or Advanced Electromagnetism. Obviously, I have taken the basic Freshman/Sophmore year E&M but I haven't taken the advance level class yet. Also, I have taken an Intro to Modern Physics class which...
  14. A

    Fundamental Ideas

    Here is an interesting question that my urge for simplification and basic/fundamental understanding has lead me to ask: -------------------------------------------------------------- What would you say are the most fundamental ideas of Physics, the most fundamental science? By fundamental what...
  15. A

    Fire vs. Water

    Why does water put fire (not oil fire) out? I understand that the bound Oxygen atoms in the H2O molecules can't be used by the fire but doesn't water contain free oxygen impurities; If not, how do fish breathe? Is it just because the amount of oxygen contained in the impurities is insignificant...
  16. A

    Photon Absorption

    If a photon does not have the required energy for changing the quantum state of a particle/atom/molecule, is it absorbed and instantaneously re-emitted with the same energy when it arrives at said particle/atom/molecule or is it not absorbed at all? Also, does it make any difference in...
  17. A

    Quark vs. Hardron mass

    Why are Hadrons so much heavier than their quark components? For example, the components of the proton have a combined mass of 12 MeV but the proton is ~950 MeV. If we look at binding energy: B=\sum{m_{components}}-m_{whole} so the Binding Energy must be a large negative number. Is this right...
  18. A

    Solar Sailing

    The photon comes in with momentum p and leaves with the same momentum in the opposite direction. The sail picks up a momentum of 2p in the original photon's direction. Energy conservation states that: h\nu_1=h\nu_2+\frac{(2p)^2^}{2m}=p_{1}c=p_{2}c+\frac{(2p)^2^}{2m} Isn't |p1|=|p2| thus...
  19. A

    Compton Scattering Using Mandel-Stam Variables

    1. Homework Statement Not homework, just for fun. I want to derive Compton Scattering equations using Mandel-Stam variables as opposed to the way that I have done it in class using the usual energy and momentum conservation 2. Homework Equations (p_\mu+p_{ei}_\mu)^2=(p'_\mu+p_e_\mu)^{2}=s p...
  20. A

    Easy Question, Nuclear Nomenclature

    1. Homework Statement What does ^{3}H(d,n)^{4}He mean? I assume it means Helium goes to tritium or is it the other way around? 2. Homework Equations None 3. The Attempt at a Solution N/A
  21. A

    Ifstream issues

    Hi everybody. I'm relatively new to C++ and am having an issue. What I need to do is take in several files and then do some data processing in each of them separately. I've tried to do this several ways and nothing has worked so far. Below is my last attempt. Basically, each file is...
  22. A

    Basic Tensor Video Lectures?

    Hi, Does anyone know of some basic video lectures covering tensors available online? Also, what is a good textbook for looking up some basic tensor examples? Maybe there is a place on the web with some good examples?
  23. A

    Convergence of Infinite Series

    Question: Test for convergence: \sum\frac{n!}{10^n} (the sum is from 1 to infinity) I tried using \frac{n^n}{10^n}\geq\frac{n!}{10^n}\geq\frac{n}{10^n} and showing that either the first one was convergent or the last one was divergent using various tests but didn't get anywhere. Any hints?
  24. A

    Geometrical Optics

    http://img140.imageshack.us/my.php?image=jonesf2238vg1.gif Problem Statement: Two prisms with the same angle but different indices of refraction are put together to form a parallel sided block of glass (see the figure). The index of the first prism is n1 = 1.48 and that of the second prism is...
  25. A

    AC Source/ Variable Resistance

    1. Homework Statement http://www.imagehosting.com/out.php/i1196840_3326.jpg In the figure, a generator with an adjustable frequency of oscillation is connected to a variable resistance R, a capacitor of C = 2.50 μF, and an inductor of inductance L. The amplitude of the current produced in the...
  26. A

    Symmetry Groups

    What does it mean to say to say that the electroweak interaction is described by a gauge field theory based on the SU(2)_{L}\timesU(1)_Y symmetry group? I know that SU(2) is a group of unitary matrices and U(1) is the circle group but I don't really see what the sentence means. I haven't taken...
  27. A

    Decay Modes of the Higgs

    I need a reference describing the possible decay modes of the Higgs. Can anyone recommend any books or websites?
  28. A

    Two Masses on a Spring

    1. Homework Statement We attach two blocks of masses m1 = 10 kg and m2 = 4 kg to either end of a spring of spring constant k = 4 N/m and set them into oscillation. Calculate the angular frequency ω of the oscillation 2. Homework Equations M_{1}{x}^{..}=k(w-x) M_{2}{w}^{..}=-k(w-x)...
  29. A

    Some Limits

    Hi, can somebody help me with this limit: The Problem Statement: limit as x approaches 1 from the left of ln(x(x-1)). Attempt I tried substitution and expansion in a Maclaurin series. This isn't homework its just a practice problem.
  30. A

    Summer plans

    My research advisor is telling me to go to CERN this summer, however I applied and was accepted to the Georgia Tech Nanotech program. I heard the Georgia Tech Nanotech program is one of the best, is that true. What do you guys think I should do? CERN or GT?
Top