[Phys-L] Re: The bulb-with-one-wire task: too tricky?

[Bernard Cleyet <anngeorg@PACBELL.NET>]

 "Besides, the screw threads (which are the only other visible part of the bulb) have the obvious function of fastening the bulb in the socket. Therefore the screw base has a function already, and is therefore eliminated from consideration - components are allowed to have only one function."

In the past I've noticed all (at least all edison based) bulbs have a
wire peeking out of the top of the base and soldered (if Cu base) or
spot welded (if Al) to the screw base.  So no longer?  I just checked
four, all with the wire connected.  Do all of you carefully select for
bases w/o the wire? I then checked four different miniature bulbs; only
one (GE 338) had a disguised connection.  It has a spot of solder on the
side (instead of the top) of the cylindrical base.  The others have a
visible wire.   If I ever try this w/ students (I think I'll try Gate
Keeper), after puzzlement, I'll suggest they look very carefully at the
base.  Incidentally a not small number of bulb types have wire or sheet
leads.  e.g. mini-xmass.   These students have never replaced open
filament ones in a string of lamps?  How about auto. dome lamps, even
head, stop, and turn lamps?

I have trouble w/ this thread,  I suppose, because I come from a
different world where children took apart things, including breaking
lamp bulbs, and dismantling Leclanché cells.  Vickie is correct; it has
become magic, but no only because it's become too hi-tek.

None of you have tried the hydraulic analogy?  The water is continually
created (like Fred Hoyle's H2), not circulated by transpiration,
evaporation, etc?

bc, who can't wait for the guarantee to expire.

p.s. I found the problem:  I wasn't able to find a CFL that revealed the
connection to the threaded part of the base.  No one uses incandescents
anymore.


Frohne,  wrote:

> I've tried the exercise in a variety of situations, including calculu=
> s-based physics.  Even physics and pre-engineering majors sometimes h=
> ave trouble with this one.   In my experience, MOST people take a whi=
> le to figure out the bulb, battery, and wire exercise.  But they cons=
> istently  DO know something about light bulbs.  Most people immediate=
> ly see the button on the end of the screw base as important. Usually,=
> they  immediately try putting the wire(s) on the bottom button, and =
> when that doesn't work, they go for the glass envelope because it's t=
> he biggest part of the bulb. Besides, the screw threads (which are th=
> e only other visible part of the bulb) have the obvious function of f=
> astening the bulb in the socket. Therefore the screw base has a funct=
> ion already, and is therefore eliminated from consideration - compone=
> nts are allowed to have only one function.  The second (electrical) f=
> uncton of the base is discovered mainly by accident, if it is discove=
> red at all.  When given two wires, people will invariably short out t=
> he battery by attaching both to the bottom button of the bulb. Nearly=
> everyone realizes that two connections are necessary and that each e=
> nd of the battery needs a wire. Several will ask if the polarity of t=
> he battery matters.  This is a reasonable question, because most peop=
> le also refer to an LED as a "butb."  The most frustrated will claim =
> that the given task is impossible either because two wires are needed=
> , or because every light bulb needs a socket.  People ARE using prior=
> common knowledge- this sequence of reasoning is very consistent. =
> =20
>
> IMHO, the battery-bulb thing is just a symptom of the bigger issue, w=
> hich is that most people have no concept of the existence of  interna=
> l mechanisms, much less the need to understand internal mechanisms. I=
> f you ask someone to explain "how it works," they'll probably say "pu=
> sh this button and turn that knob."    In everyday life, people use t=
> echnology, but they can't fix it - most technology is unfixable.  The=
> y either throw it out or get a plumber.  In everyday life, most peopl=
> e never make anything that has to do something, either.  Most people =
> even don't do arts and crafts.  "Home cooking" consists of popping so=
> mething frozen into the microwave.  Decades ago, Arthur C. Clarke wro=
> te that "Any technology, sufficiently advanced, will be indistinguish=
> able from magic."  We're there.
>
> VIckie Frohne
>
>
>
> 3. -----Original Message-----
> =46rom: Forum for Physics Educators on behalf of Robert Cohen
> Sent: Tue 2/22/2005 9:33 AM
> To: PHYS-L@LISTS.NAU.EDU
> Subject: Re: The bulb-with-one-wire task: too tricky?
> =20
> On Monday, February 21, 2005 11:47 PM, Richard Hake wrote:
>
>
> > However, I think MIT graduates - the future elite of U.S.
> > engineering/technology - should be able to figure out how to
> > make the connections from their knowledge or observations that...
>
> Is this from the Private Universe tapes?  If so, I thought the
> interviewees were Harvard graduates.  Does anyone know exactly who wa=
> s
> being interviewed?  Were they all graduates?  Does anyone know their
> majors?  I'm assuming they weren't science but I don't know.
>
> ____________________________________________________
> Robert Cohen; 570-422-3428; www.esu.edu/~bbq
> East Stroudsburg University; E. Stroudsburg, PA 18301