Recent content by shedrick94

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    I Understanding the Notation in Lagrangian Differentiation

    No you didn't scare me away. I do understand what the notation represents too. However, I saw in my notes that they had differentiated quickly the klein gordon lagrangian to get the klein gordon equation. It is defnitely a notation thing though. I don't really understand the difference between...
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    I Understanding the Notation in Lagrangian Differentiation

    I'm just in need of some clearing up of how to differentiate the lagrangian with respect to the covariant derivatives when solving the E-L equation: Say we have a lagrangian density field \begin{equation} \mathcal{L}=\frac{1}{2}(\partial_{\mu}\hat{\phi})(\partial^{\mu}\hat{\phi}) \end{equation}...
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    Differential operator acting on scalar fields

    Yeh sorry I did mean to put that A is a scalar field. Should be a bit more explicit about the problem I'm having as I wrote that last night after spending almost all my evening on it and I had given up. Basically the problem is to do with the klein gordon current with an electromagnetic field...
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    Differential operator acting on scalar fields

    Homework Statement I really cannot seem to be able to follow the logic of how you would use the product rule when using 4 vector differential operator. ∂μ is the differential operator, Aμ is a scalar field and φ and φ* is it's complex conjugate scalar field. I have the answer, I'd just really...
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    I Why does the magnetisation orient itself in the -y direction

    In magnetic resonance, if we apply a 90 degree pulse in the x direction when we have a magnetisation orientated in the z direction. Why do we get the magnetisation then orientated in the -y direction immediately after the pulse? I don't understand why it would not be in the +Y direction
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    I Why is the spin of this state equal to one?

    Why is the spin of this state s=1 then? What am I missing?
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    I Why is the spin of this state equal to one?

    Do hunds rules not say that the S= sum of all m_s values?
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    I Why is the spin of this state equal to one?

    I've just come across the spin states of a two electron system. There are 4 states possible and I am a little confused as to why the state below has values of s=1 m_s=0? [1/√2]{α(1)β(2)+α(2)β(1)} where α(i) and β(i) tell us if the particle has +ve or -ve z component of spin respectively. I...
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    Finding the Radius of Convergence for a Complex Function.

    Sorry I understand this now. The expansion was about z=i, but I understand you would just the distance between the place you are expanding around and the closest singularity.
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    I Calculus of Variations Dependent variables and constraints

    If we have a function: \begin{equation} f(x,x',y,y',t) \end{equation} and we are trying to minimise this subject to a constraint of \begin{equation} g(x,x',y,y',t) \end{equation} Would we simply have a set of two euler lagrange equations for each dependent variable, here we have x and y...
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    Finding the Radius of Convergence for a Complex Function.

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] How would you find the radius of convergence for the taylor expansion of: \begin{equation} f(z)=\frac{e^z}{(z-1)(z+1)(z-3)(z-2)} \end{equation} I was thinking that you would just...
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    Why do we want high Radiation Resistance in an antenna?

    I just read that if we have an antenna, then if the radiation resistance in the antenna is small, then the antenna is an inefficient antenna? This seems somehow counter intuitive to me. Could anyone help explain?
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    I What is the significance of αEM in Coulombic Potential calculations?

    Omg ofc it is! I was confused because it was about alpha particles. Thank you!
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    I What is the significance of αEM in Coulombic Potential calculations?

    What does the term αEM mean? I'm looking at the Coulombic Potential of an alpha particle separating from a daughter nucleus and it is stated that: VC(r)=2ZαEMħc/r Im not really sure where this term derives from? Does anyone know?
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    How to Derive the Dispersion Relation in the Heisenberg Ferromagnetic Model?

    Homework Statement There are several parts to this question, however I could complete these parts. It is just an equation used in the prior part to the question that is need to solve this: If we define \begin{equation} \sigma_{n}^{-}=\sigma_{n}^{x}+i\sigma_{n}^{y} \end{equation} and with the...
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