How effective is torricellian vaccum?

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Discussion Overview

The discussion centers around the effectiveness and absolute nature of a torricellian vacuum, particularly in the context of its application in a vacuum pump design and potential use in a cathode ray tube. Participants explore the limitations of torricellian vacuum and the implications of vapor pressure of liquids used in creating such vacuums.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes a vacuum pump design that utilizes torricellian vacuum and questions its effectiveness and whether it constitutes a complete vacuum or contains residual particles.
  • Another participant notes that man-made vacuums typically contain some residual particles, but does not assess the effectiveness of the specific vacuum mentioned.
  • A participant explains that the pressure above the mercury surface in a torricellian vacuum is determined by the vapor pressure of mercury, which is approximately 1.2μmm.Hg.
  • It is mentioned that the effectiveness of a torricellian vacuum is limited by the vapor pressure of the liquid used, and that the vacuum will reach equilibrium at this vapor pressure, containing vapor molecules from the liquid.
  • Participants inquire about which liquid would be suitable for creating a vacuum with the lowest vapor pressure.
  • There is a suggestion that for applications requiring electron passage, a more effective vacuum pump may be necessary.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the absolute effectiveness of torricellian vacuum and whether it can be considered a complete vacuum. There is no consensus on the best liquid to use for achieving the lowest vapor pressure.

Contextual Notes

The discussion highlights limitations related to the vapor pressure of liquids and the resulting implications for the effectiveness of torricellian vacuums, but does not resolve these issues.

utkarsh5
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i have designed a vacuum "pump" which uses torricellian vaccum.my "pump" just increases the size of torricellian vacuum by creating a low pressure area outside the barometer like apparatus.but that's not the question.my question is,how effective,or absolute is torricellian vaccum?is it complete vaccum,or does it still have some particles floating around?if i were to make a cathode ray tube like this,would it work?
 
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Practically all man made vacuums will have at least some residual particles floating around. I don't know how effective your vacuum is though, sorry.
 
The pressure above the mercury surface will be the vapour pressure of mercury which is about 1.2μmm.Hg
 
utkarsh5 said:
i have designed a vacuum "pump" which uses torricellian vaccum.my "pump" just increases the size of torricellian vacuum by creating a low pressure area outside the barometer like apparatus.but that's not the question.my question is,how effective,or absolute is torricellian vaccum?is it complete vaccum,or does it still have some particles floating around?if i were to make a cathode ray tube like this,would it work?

The torricellian vacuum is limited by the vapor pressure of the liquid that you use to make the vacuum. Whatever liquid you use will have a specific vapor pressure at the temperature of the liquid.
When the vacuum finally reaches equilibrium, the pressure inside the cavity will equal the vapor pressure of the liquid. The particles in the partial vacuum will be molecules of vapor from the liquid.
 
what liquid should i use then?what liquid has lowest vapor pressure?
 
utkarsh5 said:
what liquid should i use then?what liquid has lowest vapor pressure?

If you want to make a vacuum you can shoot electrons through you will probably need a decent vacuum pump.
 

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