Take a rubber dropper. Hold it by keeping its nozzle on your fingertip.
Press the rubber bulb of the dropper. What do you feel?
Immerse this nozzle half into the water in the beaker and press the bulb. Note down the observation. Observe the air bubble escaping from the nozzle.
Keeping the nozzle still inside the water, release the bulb. Note down the observation.
Now, check if it makes any difference when you press the bulb harder.
Simulator Procedure
Drag and drop the rubber dropper towards the Centre of the screen.
Click the rubber bulb of the dropper to press it.
Click on the inference button to note down the inference.
Drag and drop this dropper into the water in the beaker.
Press the rubber bulb.
Click on the inference button to note down the inference.
Keeping the nozzle still inside the water and release the bulb by clicking on it.
Click on the inference button to note down the inference.
Click the rubber bulb again.
Keeping the nozzle still inside the water and release the bulb by clicking on it.
Click on the inference button to note down the inference.
Observation
When the rubber bulb is pressed, we feel some air coming out of it on our fingertip.
When the bulb is pressed with the nozzle immersed inside water, air bubbles are seen escaping the nozzle.
On releasing the bulb in water, the water from the beaker rushes into the dropper.
A Large amount of water is filled in the dropper when the bulb is pressed harder and released.
Conclusion
When the bulb is pressed, air inside the dropper escapes out from its nozzle creating a partial vacuum inside it. This lowers the pressure inside the dropper.
On releasing the bulb, water rushes into the nozzle to fill this vacuum. This is because of the air pressure on the surface of water in the beaker.
The harder we press, the larger the amount of air that is pushed out and greater the vacuum that is created. As a result, more water is pushed in.
