but how will the speed of the deflection by the galvanometer be affected? why?  :'(

From the simulation, I can infer that if you increase the radius of the coil, the magnetic field will be less distorted inside. but urs have a current flowing in the solenoid. my qn is moving a magnet into a solenoid without any current. Can u explain in words, whether in english or chinese  :-*

By constantly inserting the magnet in and out to produce electricity, will the magnet eventually lose a bit of its magnetism? Lenz Law will eventually cause the magnet to demagnetize??