What is the Direction of the B Field from Electron Motion?

In summary, the conversation discusses the use of the right-hand rule to determine the direction of the magnetic field. The person is confused because the answer should be North, but they are getting different directions for the field. It is mentioned that different conventions exist for what the fingers and thumb represent in the right-hand rule. The person clarifies that for the first version, their thumb represents velocity, their pointer represents the force, and their middle finger represents the magnetic field. For the second version, they point their entire hand towards velocity and curl it in the direction of the force, with the thumb representing the magnetic field. It is suggested to double check the textbook or notes for the correct directions, and the person realizes their error in the first version and
  • #1
PhysKid45
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Hello PF friends.

I know what the answer is, but I do not understand why the answer is.

By the right hand rule I put my thumb west, but pointer up, and the field (middle) points North - BUT it is an electron so the field points South.
I also tried pointing my hand west, curling my fingers up, and my thumb points North - again the electron means the field should be South.

My problem is that the answer is North and I do not know why.
 
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  • #2
In using the right-hand rule, there are different conventions for what the fingers and thumb represent.

Can you state what convention you are using?
 
  • #3
For the first one my thumb is the velocity, my pointer is the direction of the force, and my middle is the B field.
For the second version I essentially point my entire hand towards velocity, and curl it in the direction of the force (curl up because the electron moves up), so the thumb is the B field.
 
  • #4
I believe these directions are incorrect for a positive charge. Double check your textbook or notes.
 
  • #5
Ok I had my pointer and my middle fingers wrong for the first one, and for the second one my thumb points in the direction of the force and curls in the direction of the B field.

Thanks!
 

1. What is "B field" in relation to electron motion?

The "B field" refers to the magnetic field that is produced by the motion of electrons. When electrons move, they create a magnetic field around them, which can be measured and observed.

2. How is the strength of the B field determined by electron motion?

The strength of the B field is determined by the speed and direction of the electron's motion. The faster the electrons move and the more concentrated their motion is in a specific direction, the stronger the resulting magnetic field will be.

3. How does the B field affect the behavior of electrons?

The B field can influence the path and velocity of electrons. When an electron moves through a B field, it experiences a force that causes it to change direction. This is known as the Lorentz force and is responsible for many electromagnetic phenomena.

4. Can the B field be manipulated or controlled?

Yes, the B field can be manipulated and controlled using various methods such as using magnets or electric currents. Scientists have also developed ways to create and manipulate B fields at the atomic and subatomic level through advanced techniques like spintronics.

5. What are the practical applications of understanding B field from electron motion?

Understanding the B field from electron motion is crucial in many fields such as particle physics, materials science, and electronics. It is used in technologies like MRI machines, particle accelerators, and generators. It also helps us understand the behavior of materials in the presence of magnetic fields, which has applications in industries such as energy and transportation.

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