我好想知道點解磁石轉動時會生電?

This is due to Lorentz Force.

There are plenty of free electrons in a conductor. When there is a relative motion between the conductor and the magnetic field (either the conductor or the magnet is moving, and the other is stationary), interaction occurs between the charges on the free electrons, which associated with them an electric field, and the magnetic filed. Such interaction between electric and magnetic fields produces a force, commonly called the Lorentz force, that drives the electrons to move. This phenomenon is known as electromagnetic induction. The movement of electrons therefore constitutes an electric current.

這叫做磁力感應--electromagnetic induction . 當磁石轉動時 , 在磁力場內之conductor such copper wire , the eletrons in the copper orbit will be subjected to a force enough to move it away .As electrons move to form current . The moving mechanical force changes to electrical energy . Energy is transformed from physical to chemical .