How does a normal pipette work?

  • Context: High School 
  • Thread starter Thread starter sameeralord
  • Start date Start date
  • Tags Tags
    Normal Work
Click For Summary

Discussion Overview

The discussion revolves around the operation of a normal pipette, specifically the mechanics of how it draws liquid into the device. Participants explore the relationship between pressure changes and liquid movement, addressing both basic principles and common practices in using a pipette.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions whether squeezing the top of the pipette creates high pressure and allows atmospheric pressure to push liquid into the pipette upon release.
  • Another participant asserts that air escapes when the top is squeezed, regardless of whether the pipette is submerged in liquid, and agrees with the initial understanding.
  • A follow-up inquiry is made regarding the practice of keeping the pipette squeezed while submerging it in liquid, questioning how air can be released again upon release if it was already squeezed.
  • A clarification is provided that the critical moment occurs when the pipette is submerged and squeezed, creating lower pressure inside, which allows the liquid to be drawn in when the pressure is released.

Areas of Agreement / Disagreement

Participants generally agree on the basic mechanics of how a pipette operates, but there is some confusion regarding the timing of air release and its effect on liquid intake, indicating that the discussion remains somewhat unresolved.

Contextual Notes

There are assumptions about the understanding of pressure dynamics and the mechanics of fluid movement that may not be fully articulated by all participants, leading to potential gaps in clarity.

sameeralord
Messages
659
Reaction score
3
Hello guys,

This might seem a basic question but my physics is not that good. So in a normal pipette when you squeeze the top bit, do you create an area of high pressure there, and then when you put in a flask with liquid and release it the air escapes, and then the atmospheric air pushes on the liquid and fluid comes into the pipette. Is that what happens? Thanks :smile:
 
Physics news on Phys.org
Air escapes when you squeeze, regardless of whether you have already put pipette in liquid or not. Other than that seems to me you are right.

--
 
Hello Borek long time,

Ok thanks for the reply. Then why do some people keep the pipette squeezed and then put it into liquid and then release it to get the liquid. When you keep it squeezed haven't you already released the air? So how is air released again when you release it?
 
There is no difference. Important moment is when pipette is submerged and squezzed. When you stop squeezing rubber creates lower pressure and sucks the liquid. Lower pressure inside, higher pressure on the outside. Whether air left the pipette before it was submerged or after doesn't change the sucking part.
 
Ok I see it was a simple question after all. Thanks for the help Borek.
 

Similar threads

High School Why are there no bubbles in a pipette when pressure is released?
  • · Replies 1 ·
Replies
1
Views
1K
High School Question about pressure of a liquid
  • · Replies 8 ·
Replies
8
Views
2K
Graduate Normal force and force of friction inside a tube
  • · Replies 2 ·
Replies
2
Views
2K
High School Does the Bernouli Effect Work On Cars?
  • · Replies 8 ·
Replies
8
Views
3K
High School Questions about momentum and force as well as normal force/friction
  • · Replies 35 ·
2
Replies
35
Views
6K
Graduate How Does Jet Injection Work in Fluid Dynamics?
  • · Replies 6 ·
Replies
6
Views
2K
High School Strain on a foil sheet separating two compartments in a cylinder
  • · Replies 4 ·
Replies
4
Views
1K
High School Actual value of normal reaction
  • · Replies 1 ·
Replies
1
Views
2K
Graduate How does a Western free reed work? (musical instruments)
  • · Replies 12 ·
Replies
12
Views
4K
Undergrad "Air Pressure" is not "the weight of the air above you"
  • · Replies 27 ·
Replies
27
Views
5K