# Physics307L:People/Mahony/Millikan

## Millikan Oil Drop Lab Summary

In this lab, my partner Ryan and I recreated the famous Millikan Oil Drop experiment to find the charge of an electron. The procedure we "followed" is outlined in the Pasco Manual.

## Results

We measured the charge for 7 droplets:

• Droplet 1: ${\displaystyle 1.78(2)\cdot 10^{-13}}$C
• Droplet 3: ${\displaystyle 2.01(2)\cdot 10^{-13}}$C
• Droplet 4: ${\displaystyle 6.58(3)\cdot 10^{-14}}$C
• Droplet 5: ${\displaystyle 5.81(2)\cdot 10^{-14}}$C
• Droplet 6: ${\displaystyle 8.16(4)\cdot 10^{-14}}$C
• Droplet 7: ${\displaystyle 6.68(3)\cdot 10^{-14}}$C
• Droplet 8: ${\displaystyle 3.40(2)\cdot 10^{-14}}$C

These charges can be compared to the elementary charge of a single electron (from wikipedia):

e = ${\displaystyle 1.602176487(40)\cdot 10^{-19}}$C

See the Analysis section of the lab notebook for the calculation of the charges of each droplet.

## Conclusions

After looking over the manual and other student's experiments I have concluded that Ryan and I did the lab wrong. For more info see the lab notebook. This could be the reason for our unexpectedly large results, or I may have made a mistake in my charge calculation that I simnply cannot find.

Despite having made a large mistake somewhere causing our data to become virtually meaningless, this lab was a good learning experience. In the future I will make sure I've read the manual correctly before starting. My suggestions for improving this lab include getting a brighter lamp for the Millikan apparatus, and finding a way to hook a CCD up to the optics, so you don't have to hunch over watching droplets for extended periods of time.