# Can a electron gun attract/repel permanent magnet?

1. May 2, 2014

### dan020350

Can it do such a thing or are the particles too small ? If it is possible can I take the electron gun out my cry is you AA batteries?

2. May 2, 2014

### ZapperZ

Staff Emeritus
Er... say that again? Especially the "... take the electron gun out my cry is you AA batteries..."

An electron beam doesn't have as much "mass" or weight as a typical magnet. If anything, the electron beam is the one that gets affected by the magnet, with very little effect on the magnet due to the electron beam.

Zz.

3. May 2, 2014

### dan020350

Sry. It is CRT. What about the toroid? Where the coils are wrap around a circle,!in the middle of the donut isn't that is how the electron beam begins? It repels out the magnet?

4. May 2, 2014

### HomogenousCow

The magnet won't feel a thing.
The magnet as a whole is orders upon orders of magnitudes more massive than the electron.

5. May 2, 2014

### UltrafastPED

I've built a variety of photo-electron guns; the steering system used magnets to deflect the beam; the magnets didn't move when the beam was switched on and off.

If you had a really strong beam - such as the beam from a quasar - then it would be a different story.

You can calculate the magnetic field for any current:
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html

Then calculate the interaction with the magnet's magnetic field ... that provides the force:
http://en.wikipedia.org/wiki/Force_between_magnets

Then use Newton's second law of motion to determine the acceleration applied to the mass of the magnet. If it is enough to overcome the force of gravity - then it will lift the magnet.

If you solve the general problem for a simple geometry you can then calculate what is required to move a given magnet.

6. May 2, 2014

Thank you

7. May 2, 2014

### davenn

No, the electron beam begins way back at the gun at the end of the tube where all the connection pins are
The coils that are placed further up the neck of the tube are used to deflect the electron beam so that it scans across the face of the tube as required

Dave

8. May 2, 2014

### dan020350

Thank you my brothers

9. May 2, 2014

### Burnerjack

On an infinitesimal scale, I would think that the electron beam DOES effect the the magnet. I base this on the fact that attraction and repulsion occur to mutual entities. As the magnet attracts or repels the beam, the force appears to both. the Earth attracts the feather and vice versa. Imperceptibly small, immeasurably so, but it must be so.