254 InductanceAdditional Problems*P32.59(a)Let Qrepresent the magnitude of the opposite charges on the plates of a parallel platecapacitor, the two plates having area Aand separation d. The negative plate creates electricfield E=∈QA20toward itself. It exerts on the positive plate force F=∈QA202toward thenegative plate. The total field between the plates is QA∈0. The energy density isuEQAQAE=∈ =∈∈=∈121220202022202. Modeling this as a negative or inward pressure, wehave for the force on one plate FPAQA==∈2022, in agreement with our first analysis.(b)The lower of the two current sheets shown createsabove it magnetic field Bk=−µ02Js±ej. Let Aand wrepresent the length and width of each sheet. Theupper sheet carries current Jwsand feels forceFBikj=×=×−=IJwJsssAAAµµ002±±±.The force per area is PFwJsA022.yxzJsJsFIG. 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 .