[领域] 电磁学 [来源] 考古题 [题目] 1. A parallel-plate capacitor is filled with a dielectric with power factor PF = 0.004 and ε=14*ε0. The plates are 350 mm square and the distance between them 12 mm. If 300V (rms) at 3MHz is applied to the capacitor , find the power dissipated as heat? 2. 有个有小疑问? Jtotal (全部的电流密度) = σE (real current density) + (dD/dt) (displacement curent) = σE + jwεE 我想问一下如果E是一个sin函数 这样的话dD/dt就会是cos函数 如此一来第二个等号就不会成立了是吗? [瓶颈] (写写自己的想法，方便大家为你解答) --

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