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Calculating surface tension with the Capillary Equation

  • #26
How would you have known? Was there a microscope in the set up?
No there was not, I simply held the tube with my hand and marked the depth and total height with a marker.
 
  • #27
haruspex
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No there was not, I simply held the tube with my hand and marked the depth and total height with a marker.
So you would not have been able to judge the contact angle. But I doubt that was a problem.
Holding the tube in your hand sounds like more of a risk. You really should have had it clamped.
Where were you making the marks? On the cup?
 
  • #28
So you would not have been able to judge the contact angle. But I doubt that was a problem.
Holding the tube in your hand sounds like more of a risk. You really should have had it clamped.
Where were you making the marks? On the cup?
No there were two marks on the capillary tube itself, one for the depth (roughly 2.7cm) and one for total height (4.6, cm on average). The difference between these values should be the h values in the capillary equation.
 
  • #29
haruspex
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No there were two marks on the capillary tube itself, one for the depth (roughly 2.7cm) and one for total height (4.6, cm on average). The difference between these values should be the h values in the capillary equation.
So you were making these marks by hand, at some depth within the surrounding cup maybe?, holding the tube with the other hand, while looking down into the cup from above... All sounds a bit awkward.
Presumably the base of the tube was resting on the base of the cup. I don't think that should affect the result, but it does not sound ideal.
 
  • #30
So you were making these marks by hand, at some depth within the surrounding cup maybe?, holding the tube with the other hand, while looking down into the cup from above... All sounds a bit awkward.
Presumably the base of the tube was resting on the base of the cup. I don't think that should affect the result, but it does not sound ideal.
I was making these markings by hand, although I used a short cup so I could look at it and mark it from the side. But yes it was a bit awkward but I did get mostly consistent results in the experiment

The base of the tube was resting on the base of the cup for every trial as well.
 

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