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Re: [Phys-l] [tap-l] glassware needed



Yes, but ....

Except for ss Dewars, I strongly suggest not attempting to use the clip on one.

When I last did kitchen physics, I used giant and large expanded polystyrene nested cups. To center the smaller I used scraps of foam. I (even) went to the trouble of covering the inner and outer cups w/ Al foil. For lids I used cups sectioned. Expanded polys. has the advantage of ignorable thermal mass.


I think the most sophisticated method is to fill the dead space w/ water and a cybernetically controlled heater. Of course, most of our suggestions defeat the intention of the experiment.


bc used his cups to find the efficiency of one of his EMR ovens (w/ out the foil!), inter alia, and was taught, long ago, (ca. 1953) to start w/ water temp. as much below RT as the expected final temp. above. [LK alluded this.]

p.s. I think the kitchen measures are the best soln. One may even nest them for additional insulation. The effectiveness of foil is a follow up experiment.

On 2008, Dec 30, , at 10:13, Dale E. Stille wrote:

Anthony,

You are making this too tough for yourself. Use small dewars / thermos bottles. You can buy either wide mouth or narrow mouth thermos bottles quite cheaply, and they are perfect for the activity you are doing. See: http://faraday.physics.uiowa.edu/em/ 5F15.10.htm for a glance at my setup.

Later,
Dale

Anthony Lapinski wrote:
Happy holidays everyone!
I want to do a lab activity using a small immersion heater and a beaker of
water. However, our beakers all have the usual sloped tops with a spout.
The clip on the immersion heater is meant for a coffee cup with straight
sides, and does not secure well to the beaker. It will fit on a tall
graduated cylinder, but then it is difficult to mix the water to get a
good temperature readings.
So I am looking for a straight sided beaker (graduated if available) to do
this experiment. I searched unsuccessfully on the interned, but only found
straight sided plastic beakers and jars. Nothing made of glass and
graduated.
Does anybody know of a source/company for what I need? Thanks!