Turn on the working power of the timer and adjust the photoelectric door of the air pump not to time.

Photoelectric gate timing error. There are many reasons why the photoelectric door of the air pump does not time when the timer is turned on: the object does not pass through the photoelectric door, the light is not blocked, the air rail is not straight, the air pressure is unstable, and the timer is not accurate. But from our experience, in many cases, the timing error of photoelectric gate is often the main source of experimental error. When the object passes through the photoelectric gate, the light is blocked, and the timer starts counting, and when the object leaves, it stops counting, so that the moving speed of the object can be calculated according to its size and moving time.