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



A variation of the "std." exercise under discussion is to use the double
filament auto bulb. It has two contacts on the bottom and the common
for the filaments is the bayonet part of the base. Connecting to the
obvious will result in dimly lighted series connection.

[Thanks to BW.]

bc, knowing this, immediately searched for the open ground in one of his
rabbit's lamp fixtures.

BTW, Costco is selling an "instant" soldering tool. Its batt. is four
AA cells (series). The work (to be soldered) completes the circuit thru
a black fixture. I think the fixture is a low resistance globar
(SiC). Any one know?

Brian Whatcott wrote:

Bayonet cap light bulbs, as commonly used in Britain, for example
have two filament contacts, and an electrically unconnected cap
with side pins provided to mechanically secure it.

I think I am reading that such a light bulb would not present
the same difficulty ass the Edison Screw bulb. Having the
possibility of a live screw cap exposed is conceptually
unattractive, no doubt.

Brian W

At 10:48 AM 2/22/2005, you wrote:


On Tuesday, February 22, 2005, at 11:21 AM, Carl Mungan wrote:



they can do it right away. So my conclusion is that it is not at all
obvious that one connection to the bulb is to the screws on the side
of the case, and that as with many things, simply "telling" them this
isn't visceral enough for them to understand. Can we blame them? Carl
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5040
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/


...see
The Physics Teacher -- April 2004 -- Volume 42, Issue 4, pp. 216-221
How Many Students Does It Take Before We See the Light?
Paula V. Engelhardt, Kara E. Gray, and N. Sanjay Rebello
Kansas State University, Manhattan, KS
ABSTRACT
Prior research suggests that students who cannot light a bulb given a
single wire, a bulb, and a battery are not able to reason correctly
regarding complete circuits. Our research shows that students believe
that the wires from the filament are connected to the base of the bulb
at the bottom. The percentage of students with this belief seems to be
dependent on the level of the introductory physics course taken
(conceptual, algebra, calculus). We have proposed three activities that
appear to aid students in developing the correct model of how a light
bulb is wired and a definition of complete circuit that classifies a
short circuit as a complete circuit but one that is not advantageous.
©2004 American Association of Physics Teachers


...on exactly this topic. Dan M

Dan MacIsaac, Assistant Professor of Physics, SUNY-Buffalo State College
222SCIE BSC, 1300 Elmwood Ave , Buffalo NY 14222 USA 716-878-3802
<macisadl@buffalostate.edu> <http://PhysicsEd.BuffaloState.edu>




Brian Whatcott Altus OK Eureka!