Sources of magnetic fields

Magnetic field of a horseshoe magnet 

Field lines start at north and end at south pole

Grip rule for the magnetic field of straight current carrying wire          Circular field       

RHR for the current and magnetic field of a loop

 RHR for magnetic dipole      Dipole field           Bar magnet          

Magnetic field of solenoid    

B = (mu) * n * I     

 Grip rule for current and magnetic field       

Classical magnetism is generated by current carrying loop ( Biot-Savart law )

Atomic magnetism originating  from the net magnetic moment of an atom

Diamagnetism ( creation of induced dipoles by external magnetic field )

Paramagnetism (alignment of permanent dipoles in the presence of  external magnetic field) 

Ferromagnetism(self alignment of permanent dipoles)     Hard magnet(in a electrical generator)    Soft magnet(in a transformer)