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hunc
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Homework Statement
I am doing the photoelectric effect experiment. And we were trying to verify the relationship between photoelectric current and distance is
[itex]I \times d^2 = k[/itex], where k is a constant.(At least I believe this to be true.)
But from the data, I kind of get a [itex]I= k d^{-2} + b [/itex]. And I got a really big b...
I was using light of [itex]\lambda = 436nm,[/itex] and diaphragm of [itex]\phi=2mm[/itex]. Here is the data.
i = [310, 198, 131] (10^-10A)
d^-2 = [1./30**2, 1./35**2, 1./40**2] (cm^-2)
And I got a relation like[tex]I = 369221.118818 d^{-2} - 101.137960591 [/tex]. I can't understand why is the b like this, big and negative.d^-2 = [1./30**2, 1./35**2, 1./40**2] (cm^-2)
Homework Equations
The Attempt at a Solution
- I am not alone. My mates have the same problem. And I checked with many of them.(I realize that three points is too small for data...)
- If distance grows really big, then current should curve. But that should put b higher than origin, while I got a minus sign. Also the line is really really linear.
- The "apparatus" was OK. Not great, but OK. I measured Planck constant right (to one part in a thousand), and I verified relation between I and \phi (of diaphragm), which has a interception of 0(to one part in a thousand again).
- My pals and myself can only come up with reasons for the interception to be positive.
4. Thanks in advance!
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