Clarifying the Basics of the Millikan Oil Drop Experiment

Click For Summary

Discussion Overview

The discussion centers on the Millikan oil drop experiment, specifically addressing the nature of the charges on the oil droplets and the plates involved. Participants explore the implications of these charges and how they relate to the experiment's setup.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether the oil droplets are positively or negatively charged and notes conflicting information between their textbook and online sources.
  • Another participant clarifies that the charge of the drops could be either positive or negative, and the charge on the bottom plate could also vary based on the battery's configuration.
  • A reference is made to Millikan's own writings, indicating a tendency for the droplets to acquire negative charges due to their greater mobility and occurrence, but acknowledges that both types of charges were studied.
  • Another participant emphasizes the importance of understanding the electric field between the plates rather than focusing solely on the charges themselves, suggesting that potential difference divided by spacing is a key factor.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the charges involved in the experiment, with no consensus reached on whether the oil droplets or the plates are definitively positive or negative.

Contextual Notes

The discussion highlights the dependence on the configuration of the battery and the definitions of charge types, as well as the potential ambiguity in educational materials regarding the experiment.

sera97
Messages
2
Reaction score
0
In the Millikan oil drop experiment, was the oil particles positively or negatively charged. and what were the charges of the plates. My textbook and what my gr.10 notes say is that the oil droplets and the bottom plate were positive, but every source online says that they were negative and that makes sense to me. Does it work either way? or have I been taught completely wrong?
 
Physics news on Phys.org
The drops investigated could be either positive or negative, and the charge on the bottom plate could be either positive or negative, depending on which way he decided to put the battery.

In fact, Millikan writes, "On account of the slightly greater mobility of the negative ion, and also on account of the somewhat greater numbers in which they occur, we found, in general, a greater tendency of the drops to take up negative than positive charges. In view, therefore, of the greater ease with which negative drops could be held for long intervals without being lost to the plates most of the drops studied have been of negative sign." But his data includes drops with both types of charge.
 
Last edited:
Thank you!
 
I think it should be pointed out that it is the Field between the plates that you need to know and not the "charges". And PD divided by the spacing would give you that.
 

Similar threads

Calculating Charge of an Electron w/ the Millikan Oil Drop Experiment
  • · Replies 12 ·
Replies
12
Views
3K
Calculating Velocity in the Millikan Oil Drop Experiment
  • · Replies 52 ·
2
Replies
52
Views
5K
Undergrad Why are some oil drops charged in Millikan's experiment?
  • · Replies 16 ·
Replies
16
Views
6K
Charge on plates in Millikan's Experiment
  • · Replies 5 ·
Replies
5
Views
2K
Millikan Oil drop lab experiment - equation for speed of drop
  • · Replies 3 ·
Replies
3
Views
2K
Graduate How Does X-Ray Ionisation Impact Millikan's Oil Drop Experiment?
  • · Replies 2 ·
Replies
2
Views
2K
Millikan Oil Drop Experiment - A few questions
  • · Replies 1 ·
Replies
1
Views
3K
Millikan Oil Drop Experiment: Determining Elementary Charge
  • · Replies 2 ·
Replies
2
Views
4K
Millikan oil drop experiment charge determination
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Millikan Oil Drop: Atom Size & Ions
  • · Replies 24 ·
Replies
24
Views
4K