Please Solve in Half an Hour Question 13 (based on material in Units 14 and 15) (a) The surface of a compact disc (CD) c

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Please Solve in Half an Hour
Question 13 (based on material in Units 14 and 15)
(a) The surface of a compact disc (CD) consists of a spiral of
engraved pits in a reflective layer, and the spacing between
adjacent lines of pits within this spiral can be used as a
reflection diffraction grating. When illuminated by white light, a
spectrum of colours can be observed in the reflected light when
viewed at certain angles.
(i) Briefly explain in your own words how these colours are
formed.
(ii) When illuminated by a beam of white light incident
perpendicular to the surface of the CD, blue light of wavelength
475 nm is observed in the first-order spectrum at an angle of
16.9°. Calculate the spacing of adjacent spirals on the surface of
the CD.