what qualitiesa good electro magnet should have ?
A good electromagnet should have the following characteristics
a) It should respond quick to change in the direction and magnitude of electric current
b) The intensity of magnetization produced for a amount of current should be large
c) The magnetic field should drop to zero on stopping the current supply
d) It's wounding wires should have low resistance and core material should have high permeability so that small power is consumed for production of magnetic field of given strength