Electric field direction with an electron?

In summary, the direction of electric field lines is from positive to negative. This means that if we put a positive charge, such as a proton, in this field, it will move in the same direction as the field. However, if we put a negative charge, such as an electron, it will move in the opposite direction of the field. This is because the electric force is directly proportional to the charge and the direction of the field. Therefore, the electric force vector will be down for a proton and up for an electron. This also explains why we use the convention of drawing field lines from positive to negative.
  • #1
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Homework Statement


If we have an electric field with a positive and negative plate:

The field lines will be going from the positive to the negative, so down.

But, if we put an electron between these two plates, it will be attracted to the positive plates, so it will have a force vector pointing up.

The electron has more potential energy at B and less at A

If the electron moves from point A to point B; was this caused by the field? Will the electric field move the electron from point A to point B, even though the electron wants to attract to the positive terminal?

So my basic question is: Will an electric fields force vector be DOWN for a proton and UP for an electron? Or will it always be DOWN (from positive to negative) no matter what? Thereby increasing the electrons potential energy?

+++++++++++++++++++++++
A

B
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Homework Equations





The Attempt at a Solution


Not really sure at the attempt, because it's not really a question from my book, but more of a question from myself.
 
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  • #2
Field lines are defined to point from positive to negative. If we draw out the lines, they'll point downward in your picture, as you said.

Now, let's remember how to relate electric forces to electric fields. If we have an electric field, E, and a charge, q, then the electric force, F, can be found with F = q*E. So if we put down a positive q (like a proton), the force will be in the direction of the field (since q won't change the sign of E). However, if we put in a negative charge (like an electron), the negative q value will cause the force to have an opposite sign from the field. We know that it will point in the opposite direction as the field.

We can see that this works. If the field lines point down, and we put in a proton, it will move down, which we just predicted. If we put in an electron, it will move up, as we just predicted and as you stated. This is actually why we use the convention of pointing field lines from positive to negative.

That's the relationship between fields and forces to remember. Does that make sense?
 
  • #3
UVW said:
Field lines are defined to point from positive to negative. If we draw out the lines, they'll point downward in your picture, as you said.

Now, let's remember how to relate electric forces to electric fields. If we have an electric field, E, and a charge, q, then the electric force, F, can be found with F = q*E. So if we put down a positive q (like a proton), the force will be in the direction of the field (since q won't change the sign of E). However, if we put in a negative charge (like an electron), the negative q value will cause the force to have an opposite sign from the field. We know that it will point in the opposite direction as the field.

We can see that this works. If the field lines point down, and we put in a proton, it will move down, which we just predicted. If we put in an electron, it will move up, as we just predicted and as you stated. This is actually why we use the convention of pointing field lines from positive to negative.

That's the relationship between fields and forces to remember. Does that make sense?

Yes, thanks. I seemed to have gotten confused, but its clear now.
 

Related to Electric field direction with an electron?

1. What is an electric field?

An electric field is a physical quantity that describes the influence that a charged object has on other charged objects within its vicinity. It is a vector quantity, meaning it has both magnitude and direction.

2. How is the direction of an electric field determined with an electron?

The direction of an electric field with an electron is determined by the direction in which a positively charged particle would move when placed in that field. Since electrons have a negative charge, their movement is opposite to the direction of the electric field.

3. What is the relationship between electric field direction and electron movement?

The direction of an electric field determines the direction in which electrons will move. Electrons will always move in the opposite direction of the electric field, from areas of high electric potential to areas of low electric potential.

4. Can the direction of an electric field change?

Yes, the direction of an electric field can change depending on the location and the distribution of charges. Electric fields are influenced by the presence of other charged objects, so their direction can change as the objects move or rearrange.

5. How is the direction of an electric field represented?

The direction of an electric field is represented by electric field lines, which show the direction of the field at different points in space. These lines are drawn perpendicular to the surface of a charged object and their density indicates the strength of the electric field at that point.

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