User:Chad A McCoy/Notebook/Jr. Lab/2008/11/10

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Planck's Lab: 11/10/2008

 * For the fifth lab experiment, I have chosen to do the Planck lab, in which I am measuring the ratio h/e and from that the value of Planck's constant.
 * For materials, I am using a Tektronix TDS1002 Two Channel Digital Storage Oscilloscope, Pasco Scientific AP-9368 h/e apparatus, Wavetek 85XT True RMS Multimeter, and a Pasco Scientific OS-9286 Mercury light source.
 * To measure the values I am using the digital multimeter and an oscilloscope to measure the value of the stopping potential of the freed electrons due to the photoelectric effect.
 * See the lab manual for more info on the apparatus.
 * To prepare to begin taking data, I allowed the light source to heat up, and focused the beam on the center of the h/e apparatus.
 * Having done this, I rotated the apparatus about the coupling and found the ultraviolet beam of the first order.

Experiment #1

 * For this experiment I am measuring the amount of time required for the electrode to recharge after discharging the capacitor, in an attempt to determine the burst time for charging.
 * To do this I am setting the oscilloscope to run a single sequence, and after discharging, covering the opening such that at removal, the amount of charge will spike, and looking at the individual burst with the oscilloscope, I will be able to measure the burst time for the different level of intensity.


 * To take these data sets I aligned the specific spectral line, and discharged the apparatus, starting a stopwatch at the time of discharge, and stopping it when it reached the max value.
 * Note: I used the max value at the max for the 20% so that the time would stop when all the data sets reached the same peak value.

Experiment #2

 * For this I am measuring Planck's constant from the value of the first and second order lines, by making a least-squares regression, of which the slope will be Planck's constant and the intercept will be the work function.


 * I had to use the orange line as yellow, because the yellow line for mercury did not resolve, and mercury's "yellow" line is generally considered to be the double yellow-orange lines at 578 and 580 nanometers.


 * For the second order measurements, I used the spectra seen to the right of the first order, and measured the ultraviolet, then violet, ..., through the yellow, and then went back to the UV and took the second data set.


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