Electrons and Parallel capacitors: after special relativity.

In summary, the student is looking for help with homework equations, and is lost because the book and teachers are not always available. The student has found a solution using the right hand rule and cross product.
  • #1
elephantorz
35
0
1.
2369912524_fa3aca5cbc_o.jpg




2. Homework Equations : are too big to post here, meaning, I will give you a link to my work:
http://farm4.static.flickr.com/3092/2369876018_5866bfb312_o.jpg"




3. The Attempt at a Solution : that's above as well, I know what the solution IS, it's at the top righthand corner of the page, boxed in.

I have been looking everywhere for homework help, since I'm doing independent study and my teacher is not always available (it's Spring Break, neither are the tutors).

I'm doing special relativity so far, and now I'm looking at electrons and positrons, parallel capacitors, etc. I have issues specifically with the easy stuff (for some reason I get the hard stuff just fine...).

If you can't read the problem above it let me know I will transcribe it, now, I have worked out that somehow, thanks to the book's example, I have to set up a right triangle. As you can see by my work (ignore the top figurings, that's just me setting up, what you want to look at are the formulas and the stuff that's worked out fully at the end of the page; also I know it's E instead of B in the last equation there, I think I was losing it by that time).

I don't know what I am doing wrong because I am lost in one sense and the book is unhelpful, I just want to understand it so I can move on to other things and other problems, btw this site rules :D.
 
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  • #2
For the electron not to be deflected, what must the net force on it be?

What's the electric force on the electron?
What's the magnetic force on the electron?
 
  • #3
Doc Al said:
For the electron not to be deflected, what must the net force on it be?

What's the electric force on the electron?
What's the magnetic force on the electron?

Is it really that simple? I just have to calculate force? Hmm...this does make sense...
 
  • #4
Yes, it's that simple. Give it another shot.
 
  • #5
Doc Al said:
Yes, it's that simple. Give it another shot.

Ok, I am assuming I have to use these:

F = qvB

F[E] = qE

But that doesn't exactly work for me, meaning, I get: 5.5544 E-16 for F and 4 E-15 for F[E] (sorry about units it's been about a year since electromagnetism, if anyone is kind enough to let me know what they are I would be grateful, V/m? ) that's nowhere near the final answer if I subtract them from each other assuming that's how I will find the net force.
 
  • #6
elephantorz said:
Ok, I am assuming I have to use these:

F = qvB

F[E] = qE

Good. (Express E in terms of the voltage.)

But that doesn't exactly work for me, meaning, I get: 5.5544 E-16 for F and 4 E-15 for F[E] (sorry about units it's been about a year since electromagnetism, if anyone is kind enough to let me know what they are I would be grateful, V/m? ) that's nowhere near the final answer if I subtract them from each other assuming that's how I will find the net force.

I have no idea what you're doing here. You have to solve for the B which will make the forces equal (and opposite, of course), so if the forces aren't equal you've done something wrong.

Don't plug in numbers until the last step. Set those forces equal and solve for B algebraically.
 
  • #7
Doc Al said:
Good. (Express E in terms of the voltage.)I have no idea what you're doing here. You have to solve for the B which will make the forces equal (and opposite, of course), so if the forces aren't equal you've done something wrong.

Don't plug in numbers until the last step. Set those forces equal and solve for B algebraically.

*Smacks forehead* yeah, it's been about two years since electromagnetism for me, it makes sense now, thanks!
 
  • #8
Wait, why is it out of the page? Right hand rule right? But how is it setup if you're not using a cross-product?
 
  • #9
Actually you are using a cross product. That magnetic force is really [itex]\vec{F} = q\vec{v}\times\vec{B}[/itex]. (The magnitude is qvB; the direction is given by the right hand rule.)
 
  • #10
Doc Al said:
Actually you are using a cross product. That magnetic force is really [itex]\vec{F} = q\vec{v}\times\vec{B}[/itex]. (The magnitude is qvB; the direction is given by the right hand rule.)

Yes, I know I am, I just wanted to get a picture of it in my head, at any rate, thanks.

Oh, and your help IS appreciated, but I suggest you don't treat people like they're stupid, asking for help doesn't mean someone warrants disrespect, if you didn't mean it to be this way (after all it is the internet) then no offense is taken.
 
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  • #11
Please point out where I gave you "disrespect".
 
  • #12
Doc Al said:
Please point out where I gave you "disrespect".

It's your tone in your writing, if you can't see it you probably didn't mean it, like I said, if you didn't, then no offense is taken.
 

1. What is the significance of electrons in the context of special relativity?

Electrons are fundamental particles that have a negative charge and play a crucial role in the theory of special relativity. Special relativity describes how objects behave at high speeds, and electrons are important because they are the building blocks of matter and are responsible for many of the properties and behaviors observed in the universe.

2. How do electrons behave in parallel capacitors according to special relativity?

In parallel capacitors, electrons are able to flow freely between the two capacitors due to the presence of an electric field. According to special relativity, the speed of electrons in this scenario can approach the speed of light, and their mass increases as they gain kinetic energy. This behavior is important to consider when designing electrical circuits.

3. Can special relativity explain the behavior of electrons in a vacuum?

Yes, special relativity can explain the behavior of electrons in a vacuum. In this scenario, electrons are able to travel at the speed of light, and their mass becomes infinite. This is known as the "mass-energy equivalence" principle, which is a fundamental concept in special relativity.

4. How does the concept of time dilation in special relativity affect electrons?

Time dilation, a phenomenon described in special relativity, states that time passes slower for objects moving at high speeds. This means that for electrons moving at near-light speeds, time appears to pass slower, and their behavior may appear to be slower to an outside observer. This has important implications for experiments and measurements involving electrons.

5. Are there any practical applications of studying electrons and parallel capacitors in the context of special relativity?

Yes, there are many practical applications of studying electrons and parallel capacitors in the context of special relativity. This knowledge is crucial in the design of electronic devices such as computers, smartphones, and other electrical circuits. It also helps us understand the behavior of particles in high-speed environments, such as particle accelerators, and is essential in the development of technologies like nuclear power and medical imaging.

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