Physics

Physics · electromagnetism

Problem

c) State under what conditions the propagation velocity of the waves is almost independent of ω\omega. Determine the velocity in this case. Given constants: When sine waves propagate in an infinite LC-grid (see the figure below) the phase of the acvoltage across two successive capacitors differs by Φ\Phi. <image_1> Formulae: cos⁡α−cos⁡β=−2⋅sin⁡(α+β2)⋅sin⁡(α−β2)\cos \alpha-\cos \beta=-2 \cdot \sin \left(\frac{\alpha+\beta}{2}\right) \cdot \sin \left(\frac{\alpha-\beta}{2}\right) sin⁡α−sin⁡β=2⋅cos⁡(α+β2)⋅sin⁡(α−β2)\sin \alpha-\sin \beta=2 \cdot \cos \left(\frac{\alpha+\beta}{2}\right) \cdot \sin \left(\frac{\alpha-\beta}{2}\right) Context question: a) Determine how Φ\Phi depends on ω,L\omega, \mathrm{L} and C\mathrm{C} ( ω\omega is the angular frequency of the sine wave). Context answer: φ=2⋅arcsin⁡(ω⋅L⋅C2)\varphi=2 \cdot \arcsin \left(\frac{\omega \cdot \sqrt{\mathrm{L} \cdot \mathrm{C}}}{2}\right) with 0≤ω≤2L⋅C0 \leq \omega \leq \frac{2}{\sqrt{\mathrm{L} \cdot \mathrm{C}}} Context question: b) Determine the velocity of propagation of the waves if the length of each unit is ℓ\ell. Context answer: ω⋅ℓ2⋅arcsin⁡(ω⋅L⋅C2)\frac{\omega \cdot \ell}{2 \cdot \arcsin \left(\frac{\omega \cdot \sqrt{\mathrm{L} \cdot \mathrm{C}}}{2}\right)}

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