Re: Writing a Physics Lab

[Jerry Hester <jhester@MTU.EDU>]

Tina,
We have students do a similar lab using 20 Ohm 20 Watt resistors.  They
can either continuously plot V vs I using data acquisition equipment and
analysis, or just step the voltage beginning at zero and record V and I.
Even with the 20 Ohm resistor we must watch and warn them not to turn the
voltage too high.  Even with this warning we sometimes have problems with
students who refuse to listen or pay attention which results in hot
resistors and damaged power supplies.  I would never consider doing this
with wires without first putting current limiting resistors into the
circuit.

Tina Fanetti wrote:

> Okay
> I have this piece of equipment.  Its a board with a bunch of wire wra=
> pped around a wooden stick.  Each coil of wire is a different length,=
>  thickness or material.  I believe the purpose of this board is to sh=
> ow how resistance depends on resistivity of the material, length and =
> cross-sectional area.
>
> Now my question is this..
> 1.  How do I write a lab activity to have students experimentally sho=
> w what R is?  I was thinking of just having them use Ohm's law and se=
> nd a fixed potential difference through the wire.  THen they could ju=
> st measure the current using a multimeter.  (not quite sure where to =
> measure current but I think I can figure that out)
>
> 2.  Now I asked some of my electronics students (dumb of me) what the=
> y thought.  They are convinced I will blow the power supply or melt t=
> he wires.  So how do I do this so that I don't wreck it. =20
>
> 3.  Does anyone have a similair lab?  I remember doing something simi=
> liar as undergraduate but apparently I had a bonfire with my lab writ=
> e-ups.....
>
> Thanks
> tina
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429

--
Jerry Hester
Jhester@mtu.edu
Laboratory/Lecture Demonstrations Coordinator
Department of Physics
Michigan Technological University
1400 Townsend Drive
Houghton, MI 49931-1295
Phone: (906) 487-2273
Fax: (906) 487-2933