1. 1
   A jeweller shines a narrow beam of white light through a triangular glass prism in a darkened room and observes a spread-out band of colours appearing on a screen behind the prism.

   (a)

   What is the name given to this splitting of white light into a band of different colours?

   [1 mark]

   • ADispersion
   • BTotal internal reflection
   • CDiffraction
   • DPolarisation

   (b)

   Which colour of visible light is refracted (bent) the most as it passes through the glass prism?

   [1 mark]

   • AYellow
   • BRed
   • COrange
   • DViolet

   (c)

   Explain, in terms of refraction and refractive index, why the glass prism splits the white light into a spread-out band of different colours rather than the light simply bending as a single, undivided beam.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A physics teacher lists the traditional seven colours of the visible spectrum, in order, to help students remember them.

   (a)

   Which of the following correctly lists these seven colours in order of increasing frequency (from lowest frequency to highest frequency)?

   [1 mark]

   • ARed, orange, yellow, green, blue, indigo, violet, but with the order of frequency and wavelength both increasing together
   • BViolet, indigo, blue, green, yellow, orange, red
   • CRed, orange, yellow, green, blue, indigo, violet
   • DGreen, blue, red, yellow, indigo, violet, orange

   (b)

   The teacher then explains the term 'monochromatic' light using a laser pointer as an example. What does it mean for a beam of light to be described as monochromatic?

   [1 mark]

   • AThe light consists of all the colours of the visible spectrum mixed together
   • BThe light consists of a single frequency (a single, pure colour)
   • CThe light has no measurable frequency at all
   • DThe light travels faster than any other type of visible light

   (c)

   Explain why a prism does not split a monochromatic laser beam into a band of colours in the way that it splits white light, even though the laser beam still undergoes refraction as it passes through the prism.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   After a rain shower, a rainbow appears in the sky when sunlight passes through countless tiny water droplets suspended in the air.

   (a)

   (a) Explain, using the concept of dispersion, why a rainbow shows a continuous band of separated colours rather than appearing as plain white light.

   [3 marks]

   (b)

   A student notices that a rainbow always appears in the part of the sky opposite to the Sun, and only when the Sun is relatively low in the sky, behind the observer, with the rain falling in front of them. Suggest and explain, referring to the paths light must take to reach the observer's eye, why a rainbow cannot be seen if the observer looks directly towards the Sun.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A museum exhibit uses a large glass prism and a bright white light source to demonstrate dispersion to visitors. A visitor asks the museum guide whether it would be possible to reverse the process, that is, to take the separated band of colours produced by the first prism and use a second, identical prism to recombine them back into a single beam of white light.

   (a)

   Explain fully, using the concept of dispersion and refraction, whether and how this recombination would be possible, describing what would need to be true about the arrangement of the second prism relative to the first.

   [6 marks]

   (b)

   The museum guide then demonstrates a variation: instead of using a second prism, she places a narrow slit and a coloured filter (which only allows a single, narrow band of colour, such as green, to pass through) in the path of the dispersed band of colours from the first prism, and directs only this single colour of light through a second, identical prism. Explain fully what the visitors would observe as this filtered, single-colour light passes through the second prism, and explain how this observation differs from, and helps confirm, the explanation you gave for full recombination in part (a).

   [6 marks]

   Total for question 4: 12 marks

End of questions