人们常常把奥斯特(Hans Christian Oersted,1777—1851)发现电磁效应看作是一个偶然的机遇。例如卡约里(F.Cajori)在1928年所写的《物理学史》中就是这样认为的。奥斯特试图通过实验来证明电磁之间的关系。1819—20年冬奥斯特在一次讲...人们常常把奥斯特(Hans Christian Oersted,1777—1851)发现电磁效应看作是一个偶然的机遇。例如卡约里(F.Cajori)在1928年所写的《物理学史》中就是这样认为的。奥斯特试图通过实验来证明电磁之间的关系。1819—20年冬奥斯特在一次讲课快要结束时,把一个非常细的铂金属线放在一个用玻璃罩着的罗盘针上,无意中发现磁针改变了位置。当他反转电流时,磁针又向相反的方向摆动。尽管磁针是放在盒子里,还是偏离了一个小角度,磁效应很弱,而且不规则。展开更多
Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potentlal are the ...Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potentlal are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.展开更多
文摘人们常常把奥斯特(Hans Christian Oersted,1777—1851)发现电磁效应看作是一个偶然的机遇。例如卡约里(F.Cajori)在1928年所写的《物理学史》中就是这样认为的。奥斯特试图通过实验来证明电磁之间的关系。1819—20年冬奥斯特在一次讲课快要结束时,把一个非常细的铂金属线放在一个用玻璃罩着的罗盘针上,无意中发现磁针改变了位置。当他反转电流时,磁针又向相反的方向摆动。尽管磁针是放在盒子里,还是偏离了一个小角度,磁效应很弱,而且不规则。
文摘Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potentlal are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.
