914_Physics ProblemsTechnical Physics

914_Physics ProblemsTechnical Physics - 254 Inductance...

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254 Inductance Additional Problems *P32.59 (a) Let Q represent the magnitude of the opposite charges on the plates of a parallel plate capacitor, the two plates having area A and separation d . The negative plate creates electric field E = Q A 2 0 toward itself. It exerts on the positive plate force F = Q A 2 0 2 toward the negative plate. The total field between the plates is Q A 0 . The energy density is uE Q A Q A E =∈ =∈ = 1 2 1 2 2 0 2 0 2 0 22 2 0 2 . Modeling this as a negative or inward pressure, we have for the force on one plate FP A Q A == 2 0 2 2 , in agreement with our first analysis. (b) The lower of the two current sheets shown creates above it magnetic field Bk =− µ 0 2 J s ± ej . Let A and w represent the length and width of each sheet. The upper sheet carries current Jw s and feels force FB i k j =×= × −= IJ w J s ss AA A µµ 00 2 ±± ± . The force per area is P F w J s A 0 2 2 . y x z J s J s FIG. P32.59(b) (c) Between the two sheets the total magnetic field is
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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