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The London equations, developed by brothers Fritz and Heinz London in 1935,〔 〕 relate current to electromagnetic fields in and around a superconductor. Arguably the simplest meaningful description of superconducting phenomena, they form the genesis of almost any modern introductory text on the subject.〔 〕 A major triumph of the equations is their ability to explain the Meissner effect,〔 〕 wherein a material exponentially expels all internal magnetic fields as it crosses the superconducting threshold. ==Formulations== There are two London equations when expressed in terms of measurable fields: : Here The last equation suffers from only the disadvantage that it is not gauge invariant, but is true only in the Coulomb gauge, where the divergence of A is zero.〔 〕 This equation holds for magnetic fields that vary slowly in space.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「London equations」の詳細全文を読む スポンサード リンク
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