Recent content by constfang

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    Graduate Self inductance of a very thin conductor, is infinity?

    Thank you very much, that cleared out the cloud a little bit for me.
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    Graduate Self inductance of a very thin conductor, is infinity?

    Hi, I was reading some text and came across this problem, the problem is also mentioned in this link from Wiki: http://en.wikipedia.org/wiki/Inductance#Self-inductance They said that it is because the 1/R now becomes infinite, this is what I'm confused about. From my understand, there would be...
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    Graduate Confusion about Gauss' law differential form

    Oh I got it now, thank you very much.
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    Graduate Confusion about Gauss' law differential form

    http://einstein1.byu.edu/~masong/emsite/S1Q50/EQMakerSL1.gif Hi guys, I have a little confusion about the Gauss' law in differential form over here, obviously, many textbook wrote it in the above form, but actually, the only place at which divE is not zero is at the locations where the...
    • constfang
    • Thread
    • Confusion Differential Differential form Form Gauss Gauss' law Law
    • Replies: 2
    • Forum: Electromagnetism
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    Undergrad Maxwell equation in optics book vs in physics book, why?

    I see, thank you.
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    Undergrad Maxwell equation in optics book vs in physics book, why?

    Thank you, just a small follow up question, what if light is transmitted in a conductive medium that have positive electric charge? does that mean everything written in the optics textbook that based on the "no-charge" assumptions will not be applicable in this case?
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    Undergrad Maxwell equation in optics book vs in physics book, why?

    I noticed that in many optics/photonics book, the Gauss law is expressed as: \nabla.E = 0 However, in wikipedia, it is \nabla.E = \frac{\rho}{\epsilon_{0}} I assume that \rho is zero in optics cases but why? I think that is because we assumed there is no electric charges on the way? then what if...
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    [thermodynamics] Is it possible problem.

    Here's a little detail about my solution: from 1st law: delta(u) = q - w q = 23kJ/kg delta(u) = u2 - u1 = 221.25 - 210.40 = 10.85 kJ/kg (u obtained from table) => w = 23kJ - 10.85 kJ/kg = 12.15kJ/kg Entropy change of the system: (treated as ideal gas): delta(s)system = Cp*ln(T2/T1)...
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    [thermodynamics] Is it possible problem.

    Genius guy! we actually only need a qH of 17.073kJ/kg to raise the temperture of air to 38Celsius, but I'm not sure if it's the answer that the professor wanted, because Cp was not given, if Cp by some reason becomes large then it's still possible.
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    [thermodynamics] Is it possible problem.

    [thermodynamics] "Is it possible" problem. Air in a piston-cylinder device, heat input Initially: T1 = 21Celsius, P1 = 2 atm Finally: T2 = 38Celsius, P2 = 2 atm = P1 (isobaric) Heat source: TH = 260Celsius, qH = 23 kJ/kg (heat input) Find: a) specific work output, w =? b) whether the...