Date: Wed Oct 28 11:46:12 2009 ** **Back to Contents ** ------------------------------------------------------------------------ **

Author: Sam Sampere

Subject: Re: c

Post:

Do you think they removed the fan in the video...?

Sam

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of Dale E. Stille
Sent: Wednesday, October 28, 2009 10:56 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] c

James, Paul, and Sammy,

Sammy....the reason you didn't see your standing waves in that movie are
twofold. One, I let the array rotate because of the nice effect. Two
and more important, Dale has not bothered to open up his microwave oven
and remove the rotating scatterer that is just below the magnetron which
is there to expressly make it so that there are NOT really defined hot
spots in the oven. Take that out and I would really get good antinodes.

James and Paul.....I think I got my last large quantity of bulbs from
Jameco, but before that I got them from Herbach and Rademan. Basically
whoever had them on sale when I needed them as you are talking large
quantities. The little array I have ( the one in the movie ) is on a
piece of 6 inch circular glass and is 16 X 16 or about 256 bulbs. The
larger array I have is on a piece of tempered glass taken from an
Overhead Projector about 11 inches square which just fits inside my
little microwave. It has an array of 35 X 40 bulbs or about 1400 bulbs
on it. Every couple of times you use it you will have to re-glue some
bulbs as the glue softens at the hot spots, but you can control that
some by making sure you only run it for 30 seconds at a time........that
is using my small 60 to 100 watt microwave.
The bulbs are regular NE-2, 6 X 19 mm neon bulbs with the pigtails. You
cut off the pigtails as close as possible and glue them to the glass or
plate.

Have fun,
Dale



Papp, James J wrote:
> Who is your vendor for those lamps?
>
> James Papp
> EMPS Lab Specialist
> College of Lake County
>
> -----Original Message-----
> From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
> Behalf Of Dale E. Stille
> Sent: Wednesday, October 28, 2009 8:20 AM
> To: tap-l@lists.ncsu.edu
> Subject: Re: [tap-l] c
>
> Sammy,
>
> Haven't made that array of neon light bulbs yet.....Ehhhh? You've had a
>
> whole weekend....what the hell you waiting for. Then you could see them
> darn standing waves.
> See: http://faraday.physics.uiowa.edu/em/5N10.56.htm
>
> Call me.
>
> Dale :)
>
>
>
>
>
> Sam Sampere wrote:
>> I never did like that experiment. First, who says there are standing
> wave in a microwave? That could be true, but I've never seen proof. And
> wouldn't the hot spots be at lambda/2?
>> I'd like her better if dad didn't screw up the physics ;)
>>
>> Later,
>>
>> Sam
>>
>> -----Original Message-----
>> From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu]
> On Behalf Of fletcher@physics.usyd.edu.au
>> Sent: Wednesday, October 28, 2009 7:14 AM
>> To: tap-l@lists.ncsu.edu; Kenn Lonnquist
>> Subject: Re: [tap-l] c
>>
>>
>> I want to enroll this future student
>>
>> http://www.youtube.com/watch?v=9O2Keu6o3i0
>>
>>
>>
>>
>> Quoting Kenn Lonnquist :
>>
>>> Brian-
>>>
>>> I have done this using fairly fresh "mini" marshmallows, and I will
>>> generally cover a whole plate with them. That way, when they do
> expand,
>>> there is not much side-to-side motion. After melting a bit (i have
> not
>>> waited for them to burn, but perhaps the marking is clearer then) I
> stop the
>>> microwave and let them cool. As they cool, they settle back down,
> without
>>> much horizontal shrinkage. Often, I can get within several percent
> from
>>> these measurements.
>>>
>>> Kenn
>>>
>>> On Tue, Oct 27, 2009 at 5:20 PM, Brian Huang
> wrote:
>>>> Matt, or anyone else out there -
>>>>
>>>> I tried this the other day, but the marshmallows just blew up
> (inflated).
>>>> I started to get some brown spots to measure, but since the
> marshmallow
>>>> moved too, I was unable to get an accurate reading. I'd love to see
> your
>>>> write-up. And, is there a specific type of marshmallow that works
> best?
>>>> Thanks!
>>>>
>>>> Brian Huang
>>>> Lafayette, CO
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Sep 11, 2009 at 8:27 AM, Matt Lowry
> wrote:
>>>>> Hi Sean,
>>>>>
>>>>>
>>>>>
>>>>> You can do it with a microwave oven rather simply by measuring the
>>>>> distance between "hot spots" on, say, a bed of marshmallows. That
> distance
>>>>> is half of a wavelength, and the standard microwave oven operates
> at a
>>>>> frequency of about 2.45 GHz. Multiply the wavelength by the
> frequency and
>>>>> you've got the speed of light. I have my students do this every
> year, many
>>>>> to within 5% of the actual value.
>>>>>
>>>>>
>>>>>
>>>>> If you're interested, let me know and I can send you the writeup I
> give to
>>>>> my students on how to make all the measurements.
>>>>>
>>>>>
>>>>>
>>>>> Cheers,
>>>>>
>>>>>
>>>>>
>>>>> Matt Lowry
>>>>>
>>>>> Lake Forest High School
>>>>>
>>>>> College of Lake County
>>>>>
>>>>> Illinois
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> *From:* tap-l-owner@lists.ncsu.edu
> [mailto:tap-l-owner@lists.ncsu.edu] *On
>>>>> Behalf Of *Lally, Sean
>>>>> *Sent:* Friday, September 11, 2009 8:17 AM
>>>>> *To:* 'tap-l@lists.ncsu.edu'
>>>>> *Subject:* [tap-l] c
>>>>>
>>>>>
>>>>>
>>>>> Folks,
>>>>>
>>>>>
>>>>>
>>>>> Any good suggestions for measuring 'c' on the cheap?
>>>>>
>>>>>
>>>>>
>>>>> Sean
>>>>>
>>>>>
>>>>>
>>> --
>>> Kenneth Lonnquist
>>> Assistant Coordinator, Introductory Physics Labs
>>> KennLonnquist@gmail.com
>>> 970.491.2540
>>> Physics Department
>>> Colorado State University
>>>
>>
>>
>> ----------------------------------------------------------------
>> This message was sent using IMP, the Internet Messaging Program.
>>
>>
>>
>
>



From tap-l-owner@lists.ncsu.edu Wed Oct 28 11:46:12 2009
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