Question

Water does not run out of a dropper unless its rubber bulb is pressed. Explain.

Answer 1

ATMOSPHERIC PRESSURE:-

1. The pressure exerted (thrust exerted on one unit area) by the air at any point on the earth is called atmospheric pressure at that point.
2. Water is held inside the dropper against the atmospheric pressure because the pressure due to the height column of liquid inside the dropper is less than the atmospheric pressure.
3. By pressing the dropper we increase the pressure inside the dropper and when it becomes greater than the atmospheric pressure the liquid comes out of the dropper.

Hence, Water does not run out of a dropper unless its rubber bulb is pressed.