Recent content by PatF

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    Old exam question about potential and thermodynamics

    Homework Statement This is a question from an old exam. The answer I have is marked wrong but I do not know why. A conducting sphere of radius a is at potential V and sits at the center of a conducting spherical shell so large that it can be considered infinite and whose potential is...
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    Why are there two Stefan Boltzmann Laws in Reif's book?

    Thanks much! I just checked and I think you are right.
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    Why are there two Stefan Boltzmann Laws in Reif's book?

    In Reif's book Fundamentals of Statistical and Thermal Physics, he labels two formulas as the Stefan-Boltzmann Law. They are both involve T^4 but the constant is different. In one, on page 376, the law is given as (pi2/15)*(kT)4/(c*hbar)3. The other, on page 388, is...
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    Reversibility, adiabatic-ness, quasi-static

    I am taking a course in statistical physics where we keep using the terms in the title. I think I understand them as stand alone terms, but I do not understand any relationships. For example, does quasi-static and reversible imply adiabatic? Does one of them imply some of the others? What...
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    What is the Electric Field in a Current Carrying Wire?

    This is a question, I think, of "unknown unknowns." I know I don't understand something but I am not quite sure what I don't understand and I am trying to work through it. So... 1) I have been following some of the threads about current in wires and electrical fields and, if I understand...
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    How long does the wheel slip before it begins to roll without slipping?

    OK. I think I have it now and I will write down the solution in case anyone else runs into the problem. I think the problem is lot subtler than it looks and the key is figuring out what it doesn't ask for as much as figuring out what it does. So... First, picture the wheel as rotating...
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    How long does the wheel slip before it begins to roll without slipping?

    "Think about the physical meaning of the phrases "rolls without slipping". What does this imply is the relationship between rotational and translational velocity?" I am terribly sorry but I HAVE thought about this but it seems absolutely pointless. You might as well say that I should...
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    How long does the wheel slip before it begins to roll without slipping?

    Homework Statement A wheel with rotational inertia I = 0.5MR^2 about its central axle is set spinning with initial angular speed w and is then lowered onto the ground so that it touches the ground with no horizontal speed. Initially it slips, but then begins to move forward and eventually...
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    Ring theory - characterizing ideals in a ring.

    This is, I think, called the localization of the integers at the prime p. It really consists of all rational numbers whose denominator is not divisible by p. So, what does an element look like when it is not invertible? (I think you already know about them.) Pick a prime, say 5, and look...
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    Question on spectroscopic notation

    Homework Statement This is a problem that was on a quiz. The quiz has already been graded and handed back and the faculty member graded very gently. (This means I passed when I think should not have.) I have thought about the answer I gave at the time and it was pretty bad. My current...
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    CE 102What is the relationship between confidence intervals and t-distributions?

    "T= (x-bar - mu initial)/(s/ sqr n) Now, what If i have no mu initial given. . . Example- Sample mean= 0.8 St. D= 0.1789 n=6" In this case, I think what you want to do is _find_ mu initial. So, plug the values you have into the above formula. This gives, T=(.8 - mu...
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    Questions About Franck-Hertz Experiment

    Naresh "3) The definition of eV is that it is the energy acquired by an electron when accelerated through a potential of 1 V (hence electron-volt). In the Franck-Hertz experiment, you accelerate electrons through some voltage, say 4.9 V. Therefore the electrons would have energy ___ eV?"...
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    Questions About Franck-Hertz Experiment

    I am not sure if this is the right place to post this so sorry if it is wrong. Be that as it may... I have just completed a lab in which we do the Franck-Hertz experiment. I am trying to understand it so I have a couple of questions I hope you can help with. 1) There is an oven into...
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    Proving Projective Modules Have Free Modules as Direct Sums

    I have seen this called Eilenberg's trick. The idea is that Q+P=F1 where Q is projective and F1 is free. Now let F=F1+F1+F1.. a countable number of times. Then, P+F is isomorphic to P+Q+P+Q+P+Q.. which is isomorphic to F.
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    Differing formulae for power emission

    I have run across two formulas for Planck's Law of Radiated Power Density. According to http://hyperphysics.phy-astr.gsu.edu/hbase/bbrc.html#c1" it is Bf(T)=((2*pi*h*c^2)/(lambda^5))(1/(e^(h*c/lambda*k*T)-1)) However, in one of your forums, the pi is missing as it is here...
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