1. 11. Radiation

2. What is radiation?

3. Radiation sources Antenna: radio waves, microwaves Atoms, molecules: light, infrared light, UV, X-rays Nuclei: Gamma rays We shall consider: Point-like source at rest with time-dependent charge distribution Accelerated point charge

4. Point-like source d radiation zone long wavelength limit

5. Multipole expansion

6. Radiation fields Dipole fields No em monopole fields Acoustic monopole fields do exist.

7. Radiated power

8. Why is the sky blue?

9. Oscillating dipole Holds in general if

10. Radiation from a moving point charge

12. Holds also for velocities small as compared to c.

13. Arbitrary velocity Power radiated by the charge Lienard’s formula

14. Bremsstrahlung v and a are parallel

16. Wilhelm Conrad Roentgen discovered X-rays 1895 Nobelprice 1901 First commercial X-ray tube 1896

17. 1960

18. Synchrotron radiation

21. BESSY synchrotron X-ray source in Berlin