Calculate Charge on Electron from Milliken Oil Drop Data

[shikagami]

Milliken Oil Drop Problem anyone? Help please.

Can some one help me with this Milliken oil drop problem.

Data from a Milliken oil drop experiment are given below. Calculate the value of the charge on an electron from this data:

Voltage needed to suspend drop (V) Drop diameter (microns)
103------ 1.1
44.7----- 1.2
127------ 1.6
175------ 1.5
11.3----- 0.9

Given:
Plate separation: 0.5cm
Density of oil: 0.95 g/mL
Gravitational constant: 9.80 m/s^2

Ok... this is what I did: q=mg/E
1. I calculated for electric field first since: E= kV/m
2. One microns is equal to 10^-6 m
3. I changed volts into kV.
4. I took the average of all 5 of the electric fields and got 67896.71718 kV/m
5. Now I solved for the mass by cubing the plate separation and canceled it with the mL... to get grams then I changed grams into kilograms to get 1.1875 x 10^-4 kg.
6. And finally I plug everything back into the equation: q=mg/E and get the answer of 2.706 x 10^-8 coulombs.

Please tell me if I did it right.

 

[shikagami]

come on anyone please help me or at least tell me if I'm in the right direction.