How to calculate the momentum of an electron
- Slides: 15
How to calculate the momentum of an electron ? Measuring the radius of curvature in a magnetic field … 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
If electrons are moving in a magnetic field, they are forced in a circle. If they lose energy as they more they go in spirals 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
The Lorentz-law helps to describe this behaviour : 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
goes into the page ! 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
The Lorentz-force is the centripetal force, which pulls the electrons to the centre : 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
Look at this sketch… …then click on it ! 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
07/17/2001 Dora Wagner & Miguel Vieira HST 2001
How do you measure the radius ? 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
r=? If we know the radius r … 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
B= ? … and if we know the strength of the magnetic field B… 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
… we are able to calculate the momentum : 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
Try it ! What to measure, what to know Scale 1 : 6. 4 For more information click here 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
In Fermilab where this picture was taken, the magnetic field was : B = 3 Tesla The charge of the observed electron is : e = 1. 6 x 10 -19 Coulomb 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
A photon travelled between the two marked points which was 11. 5 cm in the real experiment. If you want to know more, click-me 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
Can you use Pythagoras’s theorem to calculate the radius r from L and D ? BACK 07/17/2001 Dora Wagner & Miguel Vieira HST 2001
