The invention is a teaching aid, in particular a demonstrator of the left and right hand rule of electricity. Including the magnetic north pole, the magnetic south pole and the palm, the magnetic north pole and the magnetic south pole are connected together by a bracket, the palm is set between the front and rear brackets through the rotating shaft, one side of the palm is the palm of the left hand, and the other side is the palm of the right hand, and the palm is horizontal through the rotating shaft State; the front and rear ends of the palm are provided with chutes, and a conductor is arranged between the two chutes; there is an oblique groove on the palm of the left hand, and a long hole is opened on the conductor, and an external connection is inserted at the junction of the oblique groove and the elongated hole. Current arrow, there is a force arrow on the left side of the conductor, push the external current arrow upward, and the conductor will move in the direction pointed by the force arrow; there is also an oblique groove on the palm of the right hand, and a long hole is also opened on the conductor. An induced current arrow is inserted at the junction of the slot and the long hole, and a moving arrow is placed on the right side of the conductor. When the conductor is pushed to the right, the induced current arrow moves in the direction it points. The present invention can be used for demonstration at any time, and through repeated operations, the acquired knowledge is consolidated.