- 95

- 1

Also, what would be the effect of a magnetic field on a stationary (relative to the field)electron?

- Thread starter arul_k
- Start date

- 95

- 1

Also, what would be the effect of a magnetic field on a stationary (relative to the field)electron?

Mentor

- 28,293

- 4,646

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html#c2

It is always proportional to and perpendicular to both the velocity and magnetic field, so the force is 0 for a stationary electron.

- 95

- 1

The force on an electron is described by the Lorentz force law:

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html#c2

I am aware of the Lorentz force law, as I mentioned in the question I know the electron deflects at right angles to the magnetic field.

But since the electron in motion generates a magnetic field

Mentor

- 28,293

- 4,646

- 1,506

- 17

When this wire is placed in a magnetic field (between the poles of a magnet) It experiences a force in certain circumstances.

Flemings left hand rule gives the directions of current, magnetic field and resulting force.

I free electron moving with a velocity experiences the same force but the electron is not constrained by the wire and can follow a circular path.

Experimental evidence shows what happens

- 13,241

- 5,202

At this time, Lorentz has developed a classical theory for the motion of such particles in a electromagnetic field. Of course, he knew that the acceleration of such a point particle means that electromagnetic waves, the particle's wave field, are created, which carry energy and momentum away from the particle, which thus must feel a force corresponding to this energy-momentum flow.

The trouble with this, however, is that the total energy and momentum are infinite for a point particle. However, this is already true for a charge at rest. The em. field of a charge at rest is the Coulomb field (with vanishing magnetic-field components as expected from electrostatics), which has an infinite energy, but it doesn't radiate any em. waves. Also according to the principle of relativity a point charge in constant motion doesn't radiate wave fields. That's why there's one closed solution for a free point charge, which runs with constant velocity and produces a Lorentz-boosted Coulomb field (with both electric and magnetic components).

Lorentz came only to a partial solution of the problem of a charge in general (accelerated) motion: He solved the equation of motion for the particle in the given (external) electromagnetic field, neglecting the radiation reaction completely. Then he treated the radiation reaction as a perturbation, where he could subtract an infinite amount of energy, which he interpreted as (part of the) electromagnetic mass of the point charge. That was the first "renormalization" of an infinite "self energy" for an electron (in 1916, i.e., long before the analogous problem in quantum electrodynamics has been solved by Schwinger, Feynman, Tomonaga, and Dyson in ~1948-1950).

The best treatment of these problems in classical electrodynamics can be found in

F. Rohrlich, Classical Charged Particles, World Scientific.

Mentor

- 28,293

- 4,646

Basically, you cannot completely consistently treat charged point particles in classical electrodynamics.

Gold Member

- 1,221

- 75

To behave (roughly) like a magnet, the electron needs to be following a circular (or, at least, closed) path.But since the electron in motion generates a magnetic fieldwhyis the deflectionnot towardsthe magnetic field (just as a magnet would behave under the influence of a magnetic field)?

- Replies
- 2

- Views
- 1K

- Posted

- Replies
- 11

- Views
- 3K

- Posted

- Replies
- 9

- Views
- 3K

- Replies
- 2

- Views
- 576

- Replies
- 3

- Views
- 14K

- Posted

- Replies
- 3

- Views
- 3K

- Posted

- Replies
- 7

- Views
- 2K

- Replies
- 2

- Views
- 1K

We Value Quality

• Topics based on mainstream science

• Proper English grammar and spelling

We Value Civility

• Positive and compassionate attitudes

• Patience while debating

We Value Productivity

• Disciplined to remain on-topic

• Recognition of own weaknesses

• Solo and co-op problem solving

• Topics based on mainstream science

• Proper English grammar and spelling

We Value Civility

• Positive and compassionate attitudes

• Patience while debating

We Value Productivity

• Disciplined to remain on-topic

• Recognition of own weaknesses

• Solo and co-op problem solving