Oil Drop Between Two Metal Plates

In summary, the problem involves two horizontal metal plates separated by 1cm in air. A charged oil drop is balanced between the plates at a potential difference of 800 volts. The task is to find the mass of the drop using the equations dV = -E ds and W = 1/2 eE^2l. The solution involves finding the electric field between the plates and using the equilibrium condition between electric and gravitational forces. Taking into consideration the characteristics of air may be necessary for a more accurate result.
  • #1
atomicpedals
209
7

Homework Statement



Two horizontal metal plates are 1cm apart in air. An oil drop bearing a charge of one electronic unit is balanced between the plates when the potential difference between them is 800volts. Find the mass of the drop.

Homework Equations



I may need to use some combination of: dV = -E ds, and W = 1/2 eE^2l. But I'm really not even very certain on that.

The Attempt at a Solution



Really I've got nothing on this one! Any suggestions of which way to look for the solution would be much appreciated.
 
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  • #2
What's the electric field between the plates of a parallel-plate capacitor? Once you get that, write out the equilibrium condition between the electric and gravitational forces.
 
  • #3
Ok, so we have that E=V/d and then that EQ=mg (equilibrium condition), this will then yield Q=dmg/V.

I think I'm playing the right ball-game now, but this seems too simple (and doesn't yield a result that makes sense assuming my arithmetic is correct). Should my final condition take the characteristics of air into consideration?
 
Last edited:

1. What is the "Oil Drop Between Two Metal Plates" experiment?

The "Oil Drop Between Two Metal Plates" experiment is a classic physics experiment that involves observing the motion of an oil drop in an electric field between two parallel metal plates. This experiment was first conducted by Robert Millikan in 1909 to determine the charge of an electron.

2. How does the "Oil Drop Between Two Metal Plates" experiment work?

In this experiment, a small drop of oil is suspended between two parallel metal plates. The plates are charged with different electric potentials, creating an electric field between them. The oil drop is then allowed to fall through the electric field, and its motion is observed and measured. By measuring the velocity of the oil drop and the strength of the electric field, the charge of the oil drop can be calculated.

3. What is the significance of the "Oil Drop Between Two Metal Plates" experiment?

The "Oil Drop Between Two Metal Plates" experiment is significant because it provided the first direct measurement of the charge of an electron. This experiment also helped to confirm the existence of discrete electrical charges and contributed to the development of the atomic theory of matter.

4. What are the applications of the "Oil Drop Between Two Metal Plates" experiment?

The "Oil Drop Between Two Metal Plates" experiment has applications in the fields of physics, chemistry, and engineering. It is used to study the properties of charged particles, as well as to determine the charge of other small particles, such as ions and molecules. This experiment also has practical applications in the development of electronic devices and technologies.

5. Are there any variations of the "Oil Drop Between Two Metal Plates" experiment?

Yes, there are several variations of the "Oil Drop Between Two Metal Plates" experiment. One variation involves using different types of oils and measuring their velocities in the electric field. Another variation involves introducing additional forces, such as gravity or magnetic forces, to the experiment. These variations allow for further exploration and understanding of the behavior of charged particles in different conditions.

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