Imagine two parallel, (infinite) planar sheets of perfectly black material, maintained at fixed temperatures th and tl, respectively, and separated by some finite distance d. suspended in between and parallel to these sheets are n additional, separate, parallel sheets of material, all with constant reflectivity r. (by separate, we mean that none of the sheets are in actual mechanical contact). when the entire system reaches a steady state, find (a) the net flux density (energy flow per unit time per unit area) of thermal radiation between the original two sheets. (b) how does this compare to the radiation flux that would be present between the two black sheets in the absence of the n intervening sheets? (c) to provide the best insulation, should these intermediate sheets be made of very shiny or very black material, or something in between?
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Physics, 21.06.2019 19:40
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Physics, 22.06.2019 00:20
Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.
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Physics, 22.06.2019 01:30
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Physics, 22.06.2019 08:30
What properties of a moving object are used in determining the object's energy of motion
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