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This is to find resistivity of constantan. Can anyone tell me where i am going wrong.

Done the experiment at college today.
R=pl/a
p=rl/a so to put my figures in resistance =0.03 per cm cross sectional area = 0.167mm(sq.) and my results are just no where near Constantan (Eureka) 49 × 10-8
Please help is this just error or am i just not getting something.

2007-10-16 05:37:02 · 4 answers · asked by master 2 in Science & Mathematics Physics

4 answers

In order to understand the equation units must be assigned to each variables.
Area=.167 millimeters square =16.7 x10-8 meter^2
Resistance in ohms has the Units of seconds per meter.

Resistance per Unit distance = 3 seconds per meter squared..The resitivity =3 (seconds/meter^2 ) x 16.7 x10^-8 meter^2= 50.1x10^-8 seconds.
If 49 x10^-8 seconds is correct then L could be calculated,
L = R x a /4.9 x10^-7 in units of meters.

2007-10-16 09:16:10 · answer #1 · answered by goring 6 · 1 0

It may have to do with the way your rearragnged your equation:

If R = ρL/A, then

RA = ρL, and

ρ = RA/L.

Try that and see if it helps.

Good luck.

2007-10-16 12:42:26 · answer #2 · answered by Anonymous · 1 0

you've got the equation for resistivity wrong. p=Ra/l not p=Rl/a

2007-10-16 13:00:34 · answer #3 · answered by physicist 4 · 2 0

Show us your work!
What is your L ?

Go to the source below and plug in your values.

2007-10-16 12:42:24 · answer #4 · answered by Anonymous · 0 1

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