Homemade vacuum cleaner

Why do the paper scraps on the table get into the belly of our vacuum cleaner, it is actually related to the air pressure. When the motor rotates at a high speed, it will drive the fan to exhaust air from the bottle mouth to the outside of the screen, thereby forming a negative pressure inside the bottle. The external pressure of the bottle mouth is stronger than the internal pressure, and finally a suction force is generated at the bottle mouth, and the paper scraps are sucked into the bottle!