Electromagnetic field on molecule

Click For Summary

Discussion Overview

The discussion revolves around the influence of electromagnetic fields on molecules, particularly focusing on how electric and magnetic fields can affect the movement and acceleration of dipolar molecules like water. Participants explore the theoretical underpinnings, practical applications, and challenges associated with creating devices such as mass spectrometers that utilize these principles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants propose that a uniform electric field does not result in net acceleration of dipoles, as the forces on positive and negative charges cancel out, while a non-uniform field can produce a net force and acceleration.
  • One participant inquires about the necessary electrical requirements for building a mass spectrometer and questions whether it accelerates ions in a vacuum or air.
  • Another participant suggests that collisions in air could disrupt the straight trajectory of ions, potentially affecting acceleration.
  • Concerns are raised about the feasibility of constructing an accelerator in normal pressure gas, with emphasis on the impact of collisions on ion velocity.
  • Participants discuss the strength of magnetic fields needed for specific applications, such as achieving a magnetic field of 0.01–0.015 T.
  • There is a suggestion that a basic understanding of the principles involved is necessary for successfully undertaking such projects, with references to the advanced knowledge of those who built handheld mass spectrometers at MIT.

Areas of Agreement / Disagreement

Participants express differing views on the effects of electric fields on dipoles, the feasibility of constructing accelerators in air, and the necessary knowledge for such projects. The discussion remains unresolved with multiple competing perspectives on these topics.

Contextual Notes

Limitations include the need for clarity on the definitions of "electricity" in the context of creating electromagnetic fields and the specific conditions under which the discussed phenomena occur, such as the uniformity of electric fields and the pressure of the surrounding medium.

Who May Find This Useful

This discussion may be of interest to individuals exploring the principles of electromagnetism, those considering projects related to mass spectrometry, and students seeking to understand the dynamics of charged particles in electric and magnetic fields.

fysik
Messages
73
Reaction score
0
hello!

it is known that static electrical field can change the direction of movement of water dripping, etc

I suppose this can also happen with other molecules that are dipoles or somehow influenced by electrical or magnetic field

my question is what are the equation(s) that describe this influence

specifically how the strength of electrical/magnetic field can accelerate at which acceleration an amount of water eg a molecule of water, etc

I need to know what acceleration I can achieve by exposing a molecule of water to an electrical/magnetic field

thanks!
 
Physics news on Phys.org
If the electric field is uniform, there is no net force on the dipole. The opposite forces on the positive and negative charge of the dipole cancel out, and the molecule as a whole does not accelerate. The molecule just rotates because of the electric field. If the field is not uniform, then the forces on the positive and negative charges are not equal, and then the molecule has a net force on it, and it accelerates. The force, and therefore the acceleration, depends on how non-uniform the electric field is. The force is expressed in terms of the dipole moment and the gradient of the electric field.
In the standard experiment of the change in direction of dripping water, the electric field is non-uniform
 
how much electricity do I need to create a mass spectrometer, that accelerates ions?
does it accelerate ions in vacuum or air?
how fast does it accelerate ions?
 
What do you think? What will be the problem if you try it in air?
 
I think there will be collisions, but maybe the strength of the field will be adequate to maintain a fairly straight acceleration
 
how much electricity do I need to create a magnetic field of 0.01–0.015 T
 
fysik said:
I think there will be collisions, but maybe the strength of the field will be adequate to maintain a fairly straight acceleration
Every collision will change the direction of the ion's velocity. You cannot have a straight trajectory in a gas at normal pressure.
Is this for a school project? I hope you don't really think of building an accelerator.

In what units would you want the amount of "electricity" for your second question?
 
Your questions leave the impression that you are not yet understanding the basic principles for such a task.
The people at MIT were a little more advanced when they started the actual construction.
I am sure they knew how to find the "amount of electricity" they will need.

Not that is anything wrong in asking questions, don't get me wrong. :)
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 11 ·
Replies
11
Views
2K