Re: [Phys-L] [SPAM] Re: [SPAM] Re: The Make-Believe World of Real World Physics

[Bernard Cleyet <bernard@cleyet.org>]

On 2013, Jul 30, , at 15:56, Anthony Lapinski <Anthony_Lapinski@pds.org> wrote:

> I have plenty of incandescents for the rest of my teaching career. Very
> useful tools. I also break a large one open and put in series with a small
> one. Blow of the filament of the larger one to see what happens to the
> brightness of the smaller one. Great activity ("Sensitive Filament") from
> Square Wheels (Exploratorium Science Snackbook).


Iron*** (at least at RT) has ~ 50% greater temperature coefficient than W, therefore fine iron wire will make an excellent demo.  

*** which is why used to make ballast tubes.

bc has a few somewhere and failed to read his Snackbook. 

p.s the Exploratorium has a related experiment:  

Exhibit Cross Reference - Blow Out Your Toaster 


http://www.exploratorium.edu/xref/exhibits/blow_out_your_toaster.html  

Now if they had an ammeter in series, or a lamp as above, one could see the relationship of thermal expansion and conductivity, no?