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Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit

Waves

356 practice questions

Start practising (172 questions)

Topics covered

Practice questions

141–150 of 172 · Easy

  1. Question 141

    1 mark · Easy

    State what is meant by the term ‘critical angle’ when referring to light travelling from glass into air.

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  2. Question 142

    3 marks · Easy

    A ray of light travels from a type of glass (refractive index 1.62) into air.

    (a)

    Write down the equation linking the critical angle and the refractive index of the glass.

    [1 mark]
    (b)

    Calculate the value of the critical angle, to 2 decimal places.

    [2 marks]
    Answer and see the solution →

  3. Question 143

    1 mark · Easy

    Which of the following conditions must be met for total internal reflection to occur at a glass–air boundary?

    1. A.The angle of incidence must be less than the critical angle and light travels from glass to air.
    2. B.The angle of incidence must equal the critical angle and light travels from air to glass.
    3. C.The angle of incidence must be greater than the critical angle and light travels from glass into air.
    4. D.The angle of incidence must be greater than the critical angle and light travels from air into glass.
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  4. Question 144

    2 marks · Easy

    Angles measured for a glass–air interface
    Angle of incidence (i)Angle of refraction (r)
    30°19°
    40°27°
    42°90°

    Using the table above, identify the critical angle for this glass–air boundary and explain how you know.

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  5. Question 145

    2 marks · Easy

    Explain why total internal reflection does not occur when light travels from air into glass, even if the angle of incidence is large.

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  6. Question 146

    3 marks · Easy

    Optical fibres are used to carry communication signals as pulses of light.

    (a)

    State the role of total internal reflection in an optical fibre.

    [1 mark]
    (b)

    Explain, using the idea of critical angle, how the light pulse remains inside the fibre.

    [2 marks]
    Answer and see the solution →

  7. Question 147

    1 mark · Easy

    Complete the following sentence: A ray of light passing from glass into air will be totally internally reflected if the angle of incidence is _______ the critical angle.

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  8. Question 148

    3 marks · Easy

    A triangular glass prism is used in a periscope. The refractive index of the glass is 1.50.

    (a)

    Calculate the critical angle for light inside this prism. Give your answer to 2 decimal places.

    [2 marks]
    (b)

    Explain why light striking the prism face at 45° is totally internally reflected.

    [1 mark]
    Answer and see the solution →

  9. Question 149

    1 mark · Easy

    Name the two types of glass that make up an optical fibre.

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  10. Question 150

    1 mark · Easy

    What property must the core of an optical fibre have compared to the cladding to allow total internal reflection?

    1. A.The core must have a higher refractive index than the cladding.
    2. B.The core must have a lower refractive index than the cladding.
    3. C.Both core and cladding must have the same refractive index.
    4. D.The cladding must be made of plastic.
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