Charges pushed to the ends of a pole -- Faraday's law

In summary, the conversation discusses the calculation of charges that accumulate in the ends of a pole placed in a magnetic field. The equations E=Bv and ε=El are referenced, and it is established that the electric field inside a conductor must be zero. There is disagreement on which value of K to use in the equation E=KQ/R^2, but it is agreed that the charge distribution on the pole will be complicated.
  • #1
Eitan Levy
259
11

Homework Statement


We put a pole with a length of 0.2m in a magnetic field equals to 0.4T and move it with a velocity of 4m/s.
What is the value of the charges that accumulate in the ends of the pole?

Homework Equations


E=Bv
ε=El

The Attempt at a Solution


I know that E=1.6V/M and ε=0.32V (Book says it is correct). However I have no idea how to calculate the charge.
 
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  • #2
Hello again,

As you should know by now,
Eitan Levy said:
However I have no idea
doesn't count as an attempt at solution !
Assuming the pole is a conductor, what is the electric field inside ?
 
  • #3
BvU said:
Hello again,

As you should know by now,
doesn't count as an attempt at solution !
Assuming the pole is a conductor, what is the electric field inside ?
I think I understand. Assuming I am allowed to look at the charges as if they are very small, I can look at one end of the pole and say that E=KQ/R^2, and then I can get Q.
 
  • #4
What K would you use ?
 
  • #5
BvU said:
What K would you use ?
K=9*109
 
  • #6
That's for vacuum.
 
  • #7
BvU said:
That's for vacuum.
It does give the correct answer according to the book. What would you use?
 
  • #8
Eitan Levy said:
It does give the correct answer according to the book. What would you use
There's no aguing that, is there? My idea was that electric field inside a conductor has to be zero (or else the charge carriers move). Appears to boil down to the same answer.
 
  • #9
BvU said:
There's no aguing that, is there? My idea was that electric field inside a conductor has to be zero (or else the charge carriers move). Appears to boil down to the same answer.
Can you explain how?
 
  • #10
There will be electric field inside the material of the pole and there will be some charge accumulation on the pole. http://schoolbag.info/physics/sat/73.html

But the distribution of charge will be complicated. There will be charge not just at the ends of the pole. I don't see a way to evaluate the charge "in the ends of the pole".
 

1. What is Faraday's law and how does it relate to charges pushed to the ends of a pole?

Faraday's law, also known as Faraday's induction law, states that a changing magnetic field can induce an electric current in a closed circuit. This law is directly related to charges being pushed to the ends of a pole because as the magnetic field changes, the charges at the ends of the pole experience a force that causes them to move.

2. How does the strength of the magnetic field affect the charges at the ends of a pole?

The strength of the magnetic field directly affects the amount of force that is exerted on the charges at the ends of a pole. A stronger magnetic field will result in a greater force on the charges, causing them to move further away from the pole.

3. Can Faraday's law be applied to all types of poles?

Faraday's law can be applied to any type of pole, as long as there is a changing magnetic field present. This includes both permanent poles, such as those found in magnets, as well as temporary poles, such as those created by an electric current.

4. How is Faraday's law used in practical applications?

Faraday's law has many practical applications, including generators, transformers, and motors. These devices use the principle of a changing magnetic field inducing an electric current to generate electricity or convert it from one form to another.

5. Are there any limitations to Faraday's law?

Faraday's law has certain limitations, such as only being applicable to closed circuits and not being able to predict the direction of the induced current. Additionally, it only applies to a changing magnetic field and not a static one.

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