- #1

guyvsdcsniper

- 264

- 37

- Homework Statement
- Find the charge of an electron

- Relevant Equations
- q=ne

I am doing the Millikan Oil Drop experiment to determine the charge of a single electron. I have been following the lab manual provided by the manufacturer, https://hepweb.ucsd.edu/2dl/pasco/Millikans Oil Drop Manual (AP-8210).pdf.

The manual defines a simple method to calculate for the charge of the electron, which accounts for the effective viscosity of air. Page 12 and 13 of the linked lab manual defines all constants and list the method as described above.

I am using 500V from a DC power supply and have an effective viscosity of 1.809

Determining the charge essentially comes down to the velocity of the oil particle during free fall and its rising velocity under the influence of the electric field when the top capacitor plate is positive.

After analyzing over 15 particles, both respective velocities come out to be on the order of ##10^-5 to 10^-6## m/s.

Velocities on this order give a charge on the order of ##10^-10 to 10^-12## C. This is obviously too large.

I have checked the dimensional analysis of the formula provided by the manual and when done with S.I. Units, everything checks out.

After playing with numbers, I would need a velocity on the order of nm/s to get a charge on the order of ##10^-19##.

That velocity seems very excessive, given the other lab reports I have seen. Am I doing something wrong here or missing out a conversion factor?

The manual defines a simple method to calculate for the charge of the electron, which accounts for the effective viscosity of air. Page 12 and 13 of the linked lab manual defines all constants and list the method as described above.

I am using 500V from a DC power supply and have an effective viscosity of 1.809

Determining the charge essentially comes down to the velocity of the oil particle during free fall and its rising velocity under the influence of the electric field when the top capacitor plate is positive.

After analyzing over 15 particles, both respective velocities come out to be on the order of ##10^-5 to 10^-6## m/s.

Velocities on this order give a charge on the order of ##10^-10 to 10^-12## C. This is obviously too large.

I have checked the dimensional analysis of the formula provided by the manual and when done with S.I. Units, everything checks out.

After playing with numbers, I would need a velocity on the order of nm/s to get a charge on the order of ##10^-19##.

That velocity seems very excessive, given the other lab reports I have seen. Am I doing something wrong here or missing out a conversion factor?