Grade 11 Physical Sciences · Paper 1 (Physics)

Waves, Sound and Light Grade 11

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Question WE1 · Siyavula Grade 11 Physical Sciences, 5.5 Refraction, Worked example 1 · 2 marks

WE1 Calculate the speed of light through glycerine which has a refractive index of

1, 4729

.(2)

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Geometrical Optics5 past paper questions

2D and 3D Wavefronts1 past paper questions

More Waves, Sound and Light Grade 11 questions and answers

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1. Question WE3 · Siyavula Grade 11 Physical Sciences, 5.6 Snell's Law, Worked example 3 · 3 marks
WE3 A light ray with an angle of incidence of $35°$ passes from water to air. Find the angle of refraction using Snell's Law (refractive index of water $1, 333$ , of air about $1$ ). Discuss the meaning of your answer.(3)
Show the memo (3 ticks)Memo
1. ✓
  Snell's law substitution $n_{1} sin θ_{1} = n_{2} sin θ_{2}$
  $1, 33 sin 35° = 1 sin θ_{2}$
  $sin θ_{2} = 0, 763$
  1 mark · Apply Snell's law
2. ✓
  Angle of refraction $θ_{2} = 49, 7°$ or $130, 3°$
  Since $130, 3°$ is larger than $90°$ , $θ_{2} = 49, 7°$ .
  1 mark · Apply Snell's law
3. ✓
  MeaningThe light ray passes from a medium of high refractive index to one of low refractive index. Therefore, the light ray is bent away from the normal.
  1 mark · Explain refraction and total internal reflection
2. Question WE4 · Siyavula Grade 11 Physical Sciences, 5.6 Snell's Law, Worked example 4 · 3 marks
WE4 A light ray passes from water to diamond with an angle of incidence of $75°$ . Calculate the angle of refraction (refractive index of water $1, 333$ , of diamond $2, 42$ ). Discuss the meaning of your answer.(3)
Show the memo (3 ticks)Memo
1. ✓
  Snell's law substitution $n_{1} sin θ_{1} = n_{2} sin θ_{2}$
  $1, 33 sin 75° = 2, 42 sin θ_{2}$
  $sin θ_{2} = 0, 531$
  1 mark · Apply Snell's law
2. ✓
  Angle of refraction $θ_{2} = 32, 1°$
  1 mark · Apply Snell's law
3. ✓
  MeaningThe light ray passes from a medium of low refractive index to one of high refractive index. Therefore, the light ray is bent towards the normal.
  1 mark · Explain refraction and total internal reflection
3. Question WE5 · Siyavula Grade 11 Physical Sciences, 5.7 Critical angles and total internal reflection, Worked example 5 · 2 marks
WE5 Given that the refractive indices of air and water are $1, 00$ and $1, 33$ respectively, find the critical angle.(2)
Show the memo (2 ticks)Memo
1. ✓
  Snell's law with 90° refractionAt the critical angle the angle of refraction is $90°$ :
  $n_{1} sin θ_{c} = n_{2} sin 90°$
  $θ_{c} = sin^{- 1} (\frac{n _{2}}{n _{1}}) = sin^{- 1} (\frac{1}{1 , 33})$
  1 mark · Apply Snell's law
2. ✓
  Answer $θ_{c} = 48, 8°$ for light travelling from water to air
  1 mark · Apply Snell's law

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