What Are the Electric and Magnetic Fields in the Laboratory Frame?

In summary, the conversation is about an interesting question involving an infinitely long straight wire with a uniform linear charge density and its motion in two different frames. There are two parts to the question, one about the electric and magnetic fields in the laboratory frame and the other about the charge and current densities associated with the wire in the laboratory. The solution may involve Lorentz transforms and Maxwell's equations. The person who asked the question managed to solve it on their own and is looking for someone else to verify their solution. However, the moderators of this website require users to show their attempt at a solution before providing any help. The person asking the question is frustrated and looking for another website where people are more willing to share their knowledge.
  • #1
sludgethrower
9
0
Here is an interesting question (units are Gaussian):

An infinitely long strgiht wire of negligible corss-sectional area is at rest and has a uniform lineare charge density q_0 in the inertial fram K'. The frame K' (and the wire) move with a velocity v parallel to the direction of the wire with respect the the laboratory frame K.

(a) What are the electric and magnetic fields in the laboratory?

(b) What are the charge and current densities associated with the wire in the laboratory?



Relevant equations - Probably Lorentz Transforms, Maxwell Equations...



Solution Attempt - None
 
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  • #2
"None" is not an appropriate attempt at a solution.

As a hint, you might want to start by finding the electric and magnetic fields in frame [itex]K'[/itex].
 
  • #3
That first comment gabbagabbahey is really very unhelpful. What is one to do if they can't even begin to tackle a question? Surely that is is the best reason possible to ask for help! In future posts, would you prefer me to write down some wrong physics that I know is completely incorrect, just to satisfy you..?

Anyway I managed to solve this problem...
 
  • #4
sludgethrower said:
That first comment gabbagabbahey is really very unhelpful. What is one to do if they can't even begin to tackle a question? Surely that is is the best reason possible to ask for help! In future posts, would you prefer me to write down some wrong physics that I know is completely incorrect, just to satisfy you..?

Anyway I managed to solve this problem...

His comment was entirely appropriate. Please re-read the Rules link at the top of the page, especially the part about showing your attempt at a solution. We do not do your work for you -- you at least need to read your textbook and do your best to learn how to do the problems. If you have no clue how to start, read some more, do some more research -- asking at the PF is not considered doing research...
 
  • #5
When I have worked out my own solution, I want to see if it is correct...the textbook I am using provides no solution. It is best to verify the plausibility of a solution if two people have done the problem independently. Even then, you can still learn even if both solutions are correct as the other person may have taken a different approach.

If the moderators of this board are going to be stubborn, and refuse to exchange their knowledge, then this is obviously not the site for me. I actually discovered this site through the brilliant site "mathlinks": the people that use the site are genarally pure mathematicians, rather than theoretical physicists. Would someone kindly refer me to a different site where people will happily share their wisdom?
 
  • #6
sludgethrower said:
When I have worked out my own solution, I want to see if it is correct...the textbook I am using provides no solution. It is best to verify the plausibility of a solution if two people have done the problem independently. Even then, you can still learn even if both solutions are correct as the other person may have taken a different approach.

If the moderators of this board are going to be stubborn, and refuse to exchange their knowledge, then this is obviously not the site for me. I actually discovered this site through the brilliant site "mathlinks": the people that use the site are genarally pure mathematicians, rather than theoretical physicists. Would someone kindly refer me to a different site where people will happily share their wisdom?

If you are unwilling (or unable) to post the relevant equations and show your work on the homework/coursework problem, then yes, this is not the website for you. Best of luck.
 

FAQ: What Are the Electric and Magnetic Fields in the Laboratory Frame?

What is a line charge?

A line charge is a theoretical concept in physics that represents an infinitely long line of charge with a uniform charge density. It is often used to simplify calculations in electromagnetism and is analogous to a point charge in electrostatics.

How does a line charge behave in different frames of reference?

A line charge will behave differently in different frames of reference due to the effects of special relativity. As an object moves closer to the speed of light, its length contracts and its mass increases. This can cause changes in the electric and magnetic fields surrounding the line charge, leading to different observations in different frames of reference.

What is the relationship between electric and magnetic fields in a line charge?

In a stationary frame of reference, a line charge will only produce an electric field. However, in a moving frame of reference, the electric and magnetic fields are intertwined and cannot be separated. This is known as the electromagnetic field and is described by Maxwell's equations.

How is the field strength of a line charge affected by its velocity?

The field strength of a line charge will vary depending on its velocity due to the effects of special relativity. As the line charge moves closer to the speed of light, its electric and magnetic fields become stronger. This can also affect the observed charge density and other properties of the line charge.

Can a line charge be used to create a magnetic field?

In a stationary frame of reference, a line charge cannot produce a magnetic field. However, in a moving frame of reference, the electric and magnetic fields are intertwined and cannot be separated. Therefore, a moving line charge can create a magnetic field, but it is dependent on the observer's frame of reference.

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