The demonstration is the principle of energy conversion. The chemical energy in the dry battery is converted into electrical energy. The electrical energy is output to the motor through the wire. The motor converts the electrical energy into mechanical energy, which causes the motor to rotate. The motor drives the generator through the belt. The rotor in the generator rotates, cutting the magnetic force lines to generate electrical energy The mechanical energy is converted into electrical energy, that is, power generation, the emitted electricity is sent to the LED, the LED emits light, and the electrical energy is converted into light energy. The whole process is: chemical energy → electrical energy → mechanical energy → electrical energy → light energy