When we press the bulb of a dropper with its nozzle kept in water, the air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to:
$(a)$. pressure of water.
$(b)$. gravity of the earth.
$(c)$. shape of rubber bulb.
$(d)$. atmospheric pressure.

AcademicPhysicsNCERTClass 8

$(d)$. atmospheric pressure

Explanation:

When the bulb of a dropper is pressed and released, the following effects are noted:

When the bulb is pressed:

When we press the bulb of a dropper with its nozzle kept in water, the air in the dropper is seen to escape in the form of bubbles. Once the air is released from the dropper, the air pressure inside the dropper gets decreased.

When the bulb is released:

When we release the pressure on the bulb of the dropper, water gets filled in the dropper.

Reason for the rise of water in the dropper:

On releasing the bulb of the dropper, there is a rise of water inside the dropper. This is because of the air pressure difference in the dropper as the water passes from the higher pressure to the lower pressure. 

Thus, the rise of water in the dropper is due to atmospheric pressure.

Therefore, Option $(d)$ is correct. 

raja
Updated on 10-Oct-2022 13:24:47

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