1Rhombus Small Magnetic Needle with Stand Physical Experiment Teaching Instrument. 2Uses: Demonstrate the magnetic line spectrum of the linear current magnetic field, indicating the relationship between the magnetic field direction and the current direction. Demonstrate the magnetic line spectrum of the toroidal current magnetic field and their polarities. Demonstrate the magnetic line spectrum and polarity of the magnetic field of the energized solenoid, indicating the right-hand rule of the direction of the magnetic field line. 3Suitable for middle school, technical secondary school when conducting experiments or student experiment in group. 4In order to ensure the use time of the small magnetic needle, please avoid the magnetic pole and magnetism of the strong magnetic needle. 5Simple structure, easy to operate and clean.