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8 marksProperties of Waves

CAPE Physics Unit 1 · 2008 · Paper 2 · Question 5(a)(i)

A diffraction grating is illuminated by a parallel beam of light with a mixture of three wavelengths (yellow, blue, red) as shown in Figure 4, producing a spectrum with beams O, A, B, C.

Discuss with the aid of suitable diagrams the role of diffraction and interference of waves in the production of this spectrum.

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Other parts of this question

  1. 5(a)A diffraction grating is illuminated by a parallel beam of light with a mixture of three wavelengths in the yellow, blue and red parts of the visible spectrum…[1 mark]
  2. 5(a)(ii)Explain why Beam A in Figure 4 must be the blue light and also identify the colours of the Beams B and C.[1 mark]
  3. 5(a)(iii)Why does the central beam (labelled O) contain a mixture of all three colours?[1 mark]
  4. 5(b)The spectrum of sodium contains two yellow lines close together with wavelengths of 589 nm and 590 nm as shown in Figure 5. To view these lines separately an…[1 mark]
  5. 5(b)(i)Calculate the value of the HIGHEST order spectrum which can be used to view the sodium lines.[7 marks]
  6. 5(b)(ii)What is the angular separation of the two sodium lines in this spectrum?[1 mark]

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