4. (a) Explain, in detail, how x-rays are generated in a Coolidge Tube such as the one shown in the figure below (4 marks) (b) Sketch a typical X-ray emission spectrum for copper containing both continuous and characteristic X-rays. Label on your sketch Ka and K X-rays, and the short wavelength limit SWL. (4 marks) (c) Explain how characteristic X-rays are generated and the differences between Ka and K copper X-rays. (4 marks) (d) Explain the two ways that X-rays are absorbed in a material. (4 marks) (e) Explain how a thin foil of nickel can be used to filter Cu Ka from Cu K X-rays for an X-ray diffraction experiment. (4 marks)