# E- can attract e- ?

1. Dec 18, 2015

### brian.green

A charged particle have electrostatic field but this field is vectorial.
Is it like a bar magnet N and S pole? The head of a vector and a tail of an other attract each others?
A proton also have this vectorial force but p+ attract e- particles from any direction arround itself.

2. Dec 18, 2015

### blue_leaf77

Electrons can attract or repel each other when they are in a relative motion, but this is due to the magnetic force.
Bar magnet is a magnetic dipole, while a point charge is electric monopole, so they are different.

3. Dec 18, 2015

### brian.green

Point charge is monopol? But electric field is vectorial, perpendicular to the magnetic field vector. I cannot understand, electric field of an e- for example is monopol or vectorial? Vectorial doesn't mean dipole?
Wikipedia says: "It is also possible that the electron has an electric dipole moment, although this has not yet been observed (see electron electric dipole moment for more information)."

Last edited: Dec 18, 2015
4. Dec 18, 2015

### Staff: Mentor

The electric field of an electron at rest is described by vectors pointing radially inwards, directly towards the electron, from all directions. That's a monpole field.

"Vectorial" does not mean "dipole" - dipole fields are a kind of vector field, as are monopole fields (and many others).

5. Dec 18, 2015

### Staff: Mentor

It is both.
Correct.

(added: Nugatory beat me to it!)

6. Dec 18, 2015

### brian.green

At rest e- has only those many-many electric field vectors and no magnetic field at all? But what about the spin which produce magnetic field?
And when an e- is flowing it is alligned to the positive (less negative) direction and has a "head" and a "tail" and a perpendicular dipole magnetic field. At rest it has many-many vectors as you said; which one going to be the "head" when it start to flow and why that one? Is it up to the spin vector?

Last edited: Dec 18, 2015
7. Dec 19, 2015

### Staff: Mentor

When the electron is at rest, the only magnetic field it has is the tiny one produced by its tiny magnetic moment (which is the same whether the electron is moving or not). In most problems we can ignore this because it is so small.