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矩形线圈的平面垂直干均匀磁场,磁感应强度为B,线圈不动,磁场以速度vB向右运动.因通过线圈的磁通量变化,在线圈中产生感应电动势和感应电流i,磁场对电流i的安培力Fm方向向右,将驱使线圈也以速度v向右运动.显然,只有线圈的速度v小于磁场的速度vB──即异步才能有电磁感应,线圈也才能继续运动.以下我们来证明ν<νB. 设附图中的矩形线圈abed的质量为m,其回路电阻R,且在t=0时,ad边与磁场边界重合.t时刻后,磁场向右运动距离为vBt,线圈向古运动为x,则只有在面积l(vBt-x)上才有磁通量通过,即而感应电动势e及感应电流i分别为e及i的方向均由a至d… 相似文献
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Improving the membrane model by which the entropy of the black hole is studied, we study the entropy of the black hole in the non-thermal equilibrium state. To give the problem stated here widespread meaning, we discuss the (n 2)-dimensional de Sitter spacetime. Through discussion, we obtain that the black hole‘s entropy which contains two horizons (a black hole‘s horizon and a cosmological horizon) in the non-thermal equilibrium state comprises the entropy corresponding to the black hole‘s horizon and the entropy corresponding to the cosmological horizon. Furthermore, the entropy of the black hole is a natural property of the black hole. The entropy is irrelevant to the radiation field out of the horizon. This deepens the understanding of the relationship between black hole‘s entropy and horizon‘s area. A way to study the bosonic and fermionic entropy of the black hole in high non-thermal equilibrium spacetime is given. 相似文献
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避开求解黑洞背景下波动方程的困难,应用量子统计方法,直接求解轴对称Sen黑洞背景下Bose场和Fermi场的配分函数.然后利用改进的 brick-wall 方法-膜模型,计算黑洞背景下Bose场和Fermi场的熵.得到黑洞熵不但与黑洞的外视界面积有关,而且也是内视界面积的函数.在所得结论中不存在对数发散项与舍去项,也不存在黑洞视界外标量场或Dirac场为什么是黑洞熵疑难,并且给出粒子的自旋简并度对黑洞熵的影响. 当黑洞的辐射温度趋于绝对零度时,由黑洞内外视界面积决定的黑洞熵也趋于零,它满足能斯特定理,可视
关键词:
膜模型
黑洞熵
能斯特定理 相似文献
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Recently, the Hawking radiation of a black hole has been studied using the tunnel effect method. The radiation spectrum of a black hole is derived. By discussing the correction to spectrum of the rotating black hole, we obtain the canonical entropy. The derived canonical entropy is equal to the sum of Bekenstein-Havcking entropy and correction term. The correction term near the critical point is different from the one near others. This difference plays an important role in studying the phase transition of the black hole. The black hole thermal capacity diverges at the critical point. However, the canonical entropy is not a complex number at this point. Thus we think that the phase transition created by this critical point is the second order phase transition. The discussed black hole is a five-dimensional Kerr-AdS black hole. We provide a basis for discussing thermodynamic properties of a higher-dimensional rotating black hole. 相似文献
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该文采用新的广义乌龟坐标变换后,在事件视界附近直接求解Klein-Gordon方程,得到以(t,r)坐标描述的轴对称Kerr黑洞的视界位置、辐射温度.计算结果表明,考虑蒸发后Kerr黑洞的视界面是一个随时间变化的椭球面,Hawking辐射温度不仅随时间变化,而且与方位角有关.进一步分析表明Hawking辐射温度是时间坐标尺度下的补偿效应. 相似文献