Is the Lorentz magnetic force verified?

[avicenna]

Can someone provide me with some original experiments conducted which verified the Lorentz magnetic force : F = q(v X B).

Google does not give me any links except to explanations of the Lorentz force law.

 

[Doc Al]

Check out J.J. Thomson's experiments on electrons (in 1897).

 

[avicenna]

Check out J.J. Thomson's experiments on electrons (in 1897).

Thomson's well known work is in charge/mass ratio of of the electrons. Textbooks on the magnetic field don't give any hit on any original quantiative experimental verification of the magnetic force.

 

[berkeman]

Maybe the History section of this article will be of help? https://en.wikipedia.org/wiki/Mass_spectrometry

 

[Doc Al]

Thomson's well known work is in charge/mass ratio of of the electrons.

Which makes use of and confirms the Lorentz force law.

 

[ZapperZ]

Thomson's well known work is in charge/mass ratio of of the electrons. Textbooks on the magnetic field don't give any hit on any original quantiative experimental verification of the magnetic force.

I don't understand this. My students in intro physics class do this experiment as part of the course. In fact, this is a rather common undergraduate experiment in general physics courses.

Here's a demo:



.. and here's an example of the lab instruction that students do to perform this experiment:

https://ixnovi.people.wm.edu/phys251/web_manuals/emratio.pdf
http://www1.phys.vt.edu/~labs/phys3324/spring11/ph3324_lab1.pdf

So to answer the question in the title: Heck, yeah!

Zz.

 

[vanhees71]

Well, I guess the OP wanted something about the history, and I must say, I cannot point to a specific detailed source. Of course, the classical experiments are Thomson, Kaufmann, etc. Concerning the discovery of the electron, see

https://philpapers.org/rec/FALCEA-2

 

[avicenna]

I don't understand this. My students in intro physics class do this experiment as part of the course. In fact, this is a rather common undergraduate experiment in general physics courses.

Here's a demo:



.. and here's an example of the lab instruction that students do to perform this experiment:

https://ixnovi.people.wm.edu/phys251/web_manuals/emratio.pdf
http://www1.phys.vt.edu/~labs/phys3324/spring11/ph3324_lab1.pdf

So to answer the question in the title: Heck, yeah!

Zz.

The video experiment has nothing to do with verification of the magnetic force.

 

[Vanadium 50]

What exactly are you looking for?
Is it verification of the electric force?
Is it verification of the magnetic force?
Is it verification that you can vectorially add the forces?
Is it that the coefficient on the magnetic part is 1?

 

[avicenna]

What exactly are you looking for?
Is it verification of the electric force?
Is it verification of the magnetic force?
Is it verification that you can vectorially add the forces?
Is it that the coefficient on the magnetic part is 1?

The magnetic force law is : F = q(v X B). Is it verified?

 

[PeroK]

The video experiment has nothing to do with verification of the magnetic force.

I had a feeling you were going to say that!

 

[PeroK]

The magnetic force law is : F = q(v X B). Is it verified?

Why do you ask?

 

[avicenna]

Why do you ask?

I ask because I want to know the answer.

 

[PeroK]

I ask because I want to know the answer.

The Northern Lights are an excellent natural experiment in the Lorentz force:

 

[berkeman]

I ask because I want to know the answer.

Did you read through the Wikipedia link that I posted earlier?

 

[berkeman]

The magnetic force law is : F = q(v X B). Is it verified?

https://5.imimg.com/data5/PN/XP/MY-28515491/crt-tv-250x250.jpg

 

[ZapperZ]

The video experiment has nothing to do with verification of the magnetic force.

Why not? The fact that the electron beam path curved in exactly the same way that the Lorentz for predicted is a verification. Or are you completely blind of what it was demonstrating?

And what about all those undergraduate experiments that I pointed out to? Have you attempted any of them?

I don't think you even know what the magnetic Lorentz force is.

Zz.

 

[ZapperZ]

I ask because I want to know the answer.

I don't think you'd recognize the answer even if it smacked you on the face.

Just so you know, particle accelerators all over the world make use of this force. And not only that, your old TV and CRT tubes (depending on how old you are) were clear demonstration of this force. But like I said. the evidence have all been staring at you in the face, but you just don't recognize it.

Zz.

 

[avicenna]

Did you read through the Wikipedia link that I posted earlier?

I did read some of the physics involving mass spectrometry. I am not sure how it is a verification of the magnetic force law.

 

[berkeman]

I did read some of the physics involving mass spectrometry. I am not sure how it is a verification of the magnetic force law.

Are you being obtuse on purpose? What is your end game here?

 

[Ibix]

You can show that Maxwell's equations are Lorentz covariant. You can show that a pure electric field viewed from a moving frame has a magnetic component. Therefore you can re-analyse any experiment that measures the electric part of the Lorentz force law in a different frame and show that the magnetic force component behaves as expected.

Thus a test of the electric part of the Lorentz force is also a test of the magnetic part.

 

[ZapperZ]

I did read some of the physics involving mass spectrometry. I am not sure how it is a verification of the magnetic force law.

Like I said, the evidence is right in front of you, but you seem to not be able to comprehend it.

Zz.

 

[avicenna]

You can show that Maxwell's equations are Lorentz covariant. You can show that a pure electric field viewed from a moving frame has a magnetic component. Therefore you can re-analyse any experiment that measures the electric part of the Lorentz force law in a different frame and show that the magnetic force component behaves as expected.

Thus a test of the electric part of the Lorentz force is also a test of the magnetic part.

Has anyone done any experiment to verify "the electric part of the Lorentz force law in a different frame" to be correct?

 

[ZapperZ]

Has anyone done any experiment to verify "the electric part of the Lorentz force law in a different frame" to be correct?

Shouldn't you try and understand the simpler version first before trying to tackled ".. the electric part of Lorentz force law in a different frame.."? You appear to not understand either the concept of cross product or how it relates to the magnetic force on moving charge particles. How about understanding the basic concept that we cover in General Physics first?

You don't appear to be sincere about learning anything here.

Zz.

 

[Nugatory]

The magnetic force law is : F = q(v X B). Is it verified?

I have personally verified the Lorentz magnetic force (measuring the trajectory of electrons of known velocity moving through a homogeneous magnetic field) in my college physics lab, and I expect that many of the regular contributors here have similar experiences, as have generations of students before us for the past century and a half.
Thus the answer to this question (and the question in the thread title) is unambiguously "Yes".

There are also an enormous number of experiments (probably just about everything that involves using magnetic fields to manipulate the trajectories of charged particles) that would not work properly if the Lorentz force law were not valid. These are not indexed as "verifications of the Lorentz force law", but that's what they are.

 

[Nugatory]

This thread has reached the point of diminishing returns and is closed.
As with all thread closures, you may PM any mentor to ask that it be reopened if you believe that there is more to say.