Experiment result

 The more coils you put, The stronger the magnet. The bigger the battery is the more magnetism it has. The bigger the voltage, the more magnetic attraction.

Solenoid

      Solenoid- A coil of wire with an electric current.              

      
 

Magnetic Field

     The earth and a bar magnet have the same magnetic field  except earth is bigger. They both are strongest at the poles.