What Went Wrong with My Experiment?

[hagopbul]

i need to know what happened in here Read the article

 

[JoAuSc]

I'm a bit confused at what the problem is. Let me know if the following is correct:

In your experiment, you shone white light through a polarizer, then through a lens to focus it onto a photoelectric cell consisting of discs of cadmium sulphate. (Is "disc" what you meant by "cd"?) The photoelectric cell is hooked up to a circuit consisting of the cell, some other source of voltage, and an ammeter to measure the current.

For each of three polarizations (0, 30, and 60 degrees), you alter the voltage and measure the current. You have the data in the excel file and a schematic diagram in the bottom of your word document. (By the way, the schematic diagram seems to have the voltages backwards. It has the 0-degrees line on top, whereas the data has the 60-degrees line on top; is this the problem you had with the experiment?)

You say that you're expecting a straight line, but at voltage U=3, you have a dip in the graphs for all three polarizations, and you don't know why.


I'm noticing that the data isn't perfectly linear even if you neglect the points at U=3, and that the little bumps and dips seem to be correlated (that is, whenever you see a dip in one graph, you're likely to see a dip in the other two graphs at the same voltage.) (I'm also noticing that the table in the excel file doesn't match the chart.) Did you switch the polarization while looking at each voltage, or did you switch the voltage while looking at each polarization?