Recent content by Aurelius120

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    B Change in entropy of reversible isothermal process

    Since it represents the useful work, I take it to be the extra energy to be provided or the energy released after comtribution from the environment.##[-\Delta(TS)]##
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    B Change in entropy of reversible isothermal process

    Most questions we have on Gibb's Energy are either on spontaneity, or application of that formula in isothermal case.##\Delta G=\Delta H-T\Delta S## ##\Delta H=\Delta U +\Delta n_gRT## Like Unless you are referring to calorimetry of mixtures,(calculating final temperature given the value...
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    B Change in entropy of reversible isothermal process

    So the formula I learned in chemistry $$\Delta G=\Delta H-T\Delta S= \Delta U+\Delta(PV)-T\Delta S$$ is only for isothermal cases?? Since I have used it for reactions in chemistry, most chemical reactions are isothermal?? And since products and reactants are different compounds that would...
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    B Change in entropy of reversible isothermal process

    If ##d## represents a small change and ##\Delta## represents a large change Why does the formula change from $$dG=dU+d(PV)-d(TS) \text{ for small change }$$ To $$\Delta G=\Delta U+\Delta(PV) -T\Delta S \text{ for big change}$$
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    B Change in entropy of reversible isothermal process

    How do you get this?? Shouldn't it be: If ##\Delta G=\Delta H-T\Delta S## Then ##dG=dH-TdS## (Small Change) Also if ##\Delta H=\Delta U+\Delta(PV)## Then ##dH=dU+d(PV)=dU+VdP+PdV## ##dU=0## Finally $$dG=VdP+PdV-TdS$$ Correct?
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    B Change in entropy of reversible isothermal process

    So I had to find change in entropy of system in reversible isothermal process. $$T\Delta S_{sys.}=Q\implies \Delta S_{sys.}=nRln\left(\frac{V_2}{V_1}\right)$$ This was good because for isothermal process ##\Delta U=0\implies Q=W## Then I read this Throughout an entire reversible process, the...
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    B Can charges move without a field? How charges redistribute without it?

    If the outer sphere cannot be uniformly charged, the potential difference between them is not equal so they can't be treated as parallel capacitors ?
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    B Can charges move without a field? How charges redistribute without it?

    Won't that hole affect the potential (since it affects field)? Here the potential of the shells is calculated without accounting for the hole. So value of induced charge on inner sphere is wrong and therefore the rest of the calculations are wrong??
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    B Can charges move without a field? How charges redistribute without it?

    This helps to find capacitance without finding induced charges or potential on the spheres. But there also questions that ask to find charge on inner sphere which causes the problem I asked in the title
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    B Can charges move without a field? How charges redistribute without it?

    So a metallic Earth without a metallic Ionosphere is not possible. Also won't the hole affect the potential? This is how I was shown to find the potential and then capacitance: $$\frac{KQ}{b}+\frac{Kq}{a}=0\implies q=\frac{-Qa}{b}$$ Then potential difference$$=\frac{KQ}{b}-\frac{KQa}{b^2}$$...
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    B Can charges move without a field? How charges redistribute without it?

    Why though? Why should grouunding the inner sphere cause any problem to the outer sphere? It's still a metal and therefore charge will dustribute to get to maximum distance from each other right?
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    B Can charges move without a field? How charges redistribute without it?

    That gives us the capacitance. A fixed value of capacitance means a charge corresponding to that must be on the inner sphere( ##\neq 0##) which got there without an electric field ❗️ 🤔
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    B Can charges move without a field? How charges redistribute without it?

    Even in current electricity the motion of charges is explained by field developed due to emf of cell.$$I=nAev_d=nAe\left(\frac{eE}{m_e}\tau\right)$$ In this question as well, the explanation for why capacitor opposes current flow in charging is that the field for finite area charged sheet is...
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    B Can charges move without a field? How charges redistribute without it?

    So from Gauss theorem, electric field at any point inside a uniformly charged sphereical shell is zero. Thus there is no electrostatic force on the inner sphere. From what I have learnt, a field is necessary to move charges. But in this case the inner sphere acquires a charge q without any...
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    Stargazing Eye protection while watching a total solar eclipse

    I have heard that some people use X-Ray or CT-scan reports (what's that black film called?) to view eclipses. I don't know how well they work though?
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