Recent content by aperception

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    Finding an Integrating Factor for a Diffential Equation

    Anyone? I know there are lots of Boas lovers on here
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    Finding an Integrating Factor for a Diffential Equation

    Integrating Factors for ODEs (Question from Boas) Find an integrating factor by inspection to make the below differential equation exact. (y^2-xy)dx+(x^2+xy)dy=0 I've been inspecting, but I'm not seeing it! Is there a way to analyze this in my head that will lead me more easily to the...
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    BJT(npn) physical operation help

    I realize that this thread is 5 years old, but I spent a bit of time thinking about it, and feel that I can add a little more physical clarity for anyone who searches and finds this thread. I will discuss a pnp transistor with geometry as per figure 5.6 in Sze (attached). In the forward active...
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    Reflection at a conducting surface

    OK thanks for your reply, I guess I will take your word for it (that there can't be both J and K in a conductor) until I get around to studying E&M at graduate level.
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    Reflection at a conducting surface

    Sorry to revive this thread again, but I'm puzzling over it myself, and I'm still not convinced by any of the answers to the OP question - what exactly does Griffiths mean by "this would require an infinite electric field at the boundary"? What are the relevant equations to see that this is...
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    MATLAB Why Does MATLAB's Symbolic Math Toolbox Struggle with Some Definite Integrals?

    Does anybody know much about how this works? I can't understand why it doesn't give me an answer for definite integrals sometimes... e.g. in Matlab R2011a: syms x a; int(x/sqrt(x^2+a^2)) gives the answer (a^2 + x^2)^(1/2) as expected. But int(x/sqrt(x^2+a^2),0,10) gives - Warning...
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    Recurrence relation for an integral equation

    That is very clever, it worked great thank you!
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    Recurrence relation for an integral equation

    Hi guys, would appreciate any help with this problem. It's from a graduate school entrance examination which I am practicing. problem statement When n is a natural number, the indefinite integral I_n is defined as I_n=\int\frac{1}{(x^2+a^2)^n}dx Here, a is a constant real number, and...
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    Analytically finding the stress tensor field

    http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/index.htm" was quite useful... and there's a reference in one of the modules to a book called "Roark's Formulas for Stress and Strain" which gives solutions to most of the problems for which analytical solutions exist. From a skim...
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    Analytically finding the stress tensor field

    I also need to know about a related problem although not for homework... I'm trying to do an order of magnitude calculation for a photoelasticity experiment. If I have a cube/cuboid with a point force applied normal to one of the surfaces in the center and an equal and opposite force applied...
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