http://xaf.xanga.com/5c6c765740432183306379/z140383926.bmp
Under an external force,a metal rod is moving with a uniform spped v on a
metal rail place in a uniform magnetic field.
點解個metal rod郁,佢o既magnetic field就change左??
個metal rod唔係係一個uniform magnetic field入面咩??
更新1:
但根據Faraday's law of lectromagnetic induction 唔係當magnetic field change先有induced current咩???