Specifications: Material: Magnet, plastic;  Size: 12 x 9cm;  Scope Of Application: Wire magnetic field physics teaching instrument;     Features: - Good teaching tools;  - Has a good experimental display effect.     How To Use? Type A:  - Connect the wires, screw the two suspension rods into the holes with the soldering holes, and hang the square coil. One end of the U-shaped magnet is placed on the bottom plate, and the other end is placed in the square coil hole. Inside, press the Type A switch, slide the varistor and 2A power supply (self-prepared), voltage DC4-6V.  - Observe that the square coil composed of the wire and the suspension column rotates at an angle in a certain direction, observes the change of the direction of movement of the conductive tube in the magnetic field, and explores its law.  - What is the change in the magnitude of the current? Experiments show that the energized wire is subjected to the force in the magnetic field, and the direction of the force is related to the direction of the current, the direction of the magnetic induction line, and the magnitude of the current. When the direction of the current or the direction of the magnetic induction line becomes opposite, the direction in which the energized wires are subjected to force also becomes opposite.  Type B:  - Connect the wire, sliding varistor and single-pole switch to the DC output of the 2A low-voltage power supply. Adjust the power supply voltage to 6-8V. Place the hollow copper tube on the conductor rolling guide frame and open the power switch. The copper tube rolls forward, indicating the working principle of the DC motor. Observe the change of the direction of the positive and negative conductors of the experimental power supply and explore its law.  - What is the change in the current? The experiment proves that the magnetic field exerts a force on the energized wire perpendicular to the direction of the magnetic field, and its magnitude is proportional to the magnitude of the current I flowing through the wire and the magnetic induction intensity B of the magnetic field, and the direction is in accordance with the left-hand rule.     Notice: 1. The current should not be too large during the experiment to avoid heating of the wires and the conductive tubes;  2. After the instrument is used, place it in a cool dry place.     Package Included: 1 Pcs x Base;  1 Pcs x U-shaped Magnet;  1 Pcs x Square Coil;  2 Pcs x Suspension Rod;  2 Pcs x Rail;  1 Pcs x Hollow Copper Tube;  2 Pcs x Power Cord