1. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 How to calculate the momentum of an electron ? Measuring the radius of curvature in a magnetic field …

2. 07/17/2001Dora 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

3. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 The Lorentz-law helps to describe this behaviour :

4. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 goes into the page !

5. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 The Lorentz-force is the centripetal force, which pulls the electrons to the centre :

6. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 Look at this sketch… …then click on it !

7. 07/17/2001Dora Wagner & Miguel Vieira HST 2001

8. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 How do you measure the radius ?

9. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 r = ? If we know the radius r …

10. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 B = ? … and if we know the strength of the magnetic field B…

11. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 … we are able to calculate the momentum :

12. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 Try it ! For more information click here For more information click here What to measure, what to know What to measure, what to know Scale 1 : 6.4

13. 07/17/2001Dora 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 = 1.6x10 -19 Coulomb

14. 07/17/2001Dora 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

15. 07/17/2001Dora Wagner & Miguel Vieira HST 2001 Can you use Pythagoras’s theorem to calculate the radius r from L and D ? BACK