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DP IB Physics: SL

Topic Questions

Home / IB / Physics: SL / DP / Topic Questions / 4. Waves / 4.3 Wave Characteristics / Structured Questions


4.3 Wave Characteristics

Question 1a

Marks: 3
(a)
Outline what is meant by the terms
 
(i)
Wavefront
[2]
(ii)
Ray
[1]
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    Key Concepts
    Wavefronts

    Question 1b

    Marks: 1
    (b)
    Complete the following sentence by placing a tick (✓) next to the correct answer:
     
    The distance between two consecutive wavefronts is equal to the:
       wavelength
       frequency
       amplitude
    [1]
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      Key Concepts
      Wavefronts

      Question 1c

      Marks: 4
      (c)
      On the grid below, draw scale diagrams showing the wavefronts for
       
      (i)
      A plane wave with a wavelength of 1 cm.
       [2]
      (ii)
      A circular wave with a wavelength of 1 cm.

      [2]

      On both diagrams, show with arrows, the direction of propagation.

      8-1-ib-sl-sq1c-q-grid

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        Key Concepts
        Wavefronts

        Question 1d

        Marks: 2
        (d)
        Complete the following sentences by circling the correct word:
         
        The higher the frequency of an oscillation, the longer / shorter the wavelength and the closer / further apart the wavefronts are to / from one another.
         
        The lower the frequency of the oscillation, the longer / shorter the wavelength and the closer / further apart the wavefronts are to / from one another.
        [2]
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          Key Concepts
          Wavefronts

          Question 2a

          Marks: 2
          (a)
          Match the terms power and intensity to their correct definitions and SI units.
          4-3-q2a

          [2]

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            Key Concepts
            Amplitude & Intensity

            Question 2b

            Marks: 2

            A point source radiates light waves in all directions. The intensity, I, of the waves is related to the power, P, by the equation:

            I equals fraction numerator P over denominator 4 straight pi r squared end fraction

            The relationship between the distance from the point source, r, and the intensity of the wave are shown to follow an inverse square law.

            (b)
            Describe what is meant by the term inverse square law in this context.
            [2]
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              Key Concepts
              Amplitude & Intensity

              Question 2c

              Marks: 2
              (c)
              Describe the relationship between intensity, I, and amplitude, A.
              [2]
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                Key Concepts
                Amplitude & Intensity

                Question 2d

                Marks: 2

                Two students are investigating the relationship between intensity and amplitude. The graphs below show the variation of the displacement of a particle with time when two progressive waves X and Y pass separately through a medium.

                4-3-q2d-question-stem-sl-sq-easy-phy

                The intensity of wave X is I0. Student 1 says that the intensity of wave Y must be I subscript 0 over 2 but Student 2 thinks it must be I subscript 0 over 4.

                (d)
                Determine, using the relationship from part (c), which student is correct.

                [2]

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                  Key Concepts
                  Amplitude & Intensity

                  Question 3a

                  Marks: 2
                  (a)
                  Outline what is meant by the principle of superposition.
                  [2]
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                    Key Concepts
                    Superposition

                    Question 3b

                    Marks: 1

                    Two pulses travel toward one another as shown in the diagram.

                    4-3-3b-question-stem-sl-sq-easy-phy

                    (b)
                    Sketch the resultant displacement as the pulses superpose.
                    [1]
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                      Key Concepts
                      Superposition

                      Question 3c

                      Marks: 1

                      Two pulses travel in opposing directions as shown in the diagram. When the pulses meet, they superpose.

                      4-3-3c-question-stem-sl-sq-easy-phy

                      (c)
                      Draw the resultant peak as the pulses superpose.
                      [1]
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                        Key Concepts
                        Superposition

                        Question 3d

                        Marks: 4
                        (d)
                        Distinguish between the terms constructive interference and destructive interference.
                        [4]
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                          Key Concepts
                          Superposition

                          Question 4a

                          Marks: 2
                          (a)
                          Distinguish between the terms polarised and unpolarised light.
                          [2]
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                            Key Concepts
                            Polarisation

                            Question 4b

                            Marks: 2
                            (b)
                            Outline the reason why a sound wave cannot be polarised.
                            [2]
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                              Key Concepts
                              Polarisation

                              Question 4c

                              Marks: 1

                              Unpolarised light is passed through a polariser as shown in the diagram.

                              4-3-4c-question-stem-1-sl-sq-easy-phy

                              (c)
                              Draw a double-headed arrow to indicate the resultant orientation of the polarised light.
                              [1]
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                                Question 4d

                                Marks: 3

                                Polarised light is passed through polarising filter A as shown in the diagram.

                                2c-figure-1

                                An identical polarising filter B is placed directly after A at 90º.

                                (d)
                                State and explain what happens to the intensity of the light after it is incident on polarising filter B.
                                [3]
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                                  Question 5a

                                  Marks: 1
                                  (a)
                                  Outline the change in intensity of the incident unpolarised light as it passes through a polariser.
                                  [1]
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                                    Key Concepts
                                    Malus's Law

                                    Question 5b

                                    Marks: 1

                                    Unpolarised light is passed through a polarising filter as shown in the diagram. A second polarising filter called an analyser is placed in sequence. 

                                    4-3-5b-question-stem-sl-sq-easy-phy

                                    (b)
                                    Compare the intensity of the analysed light to the intensity of the unpolarised light.
                                    [1]
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                                      Key Concepts
                                      Malus's Law

                                      Question 5c

                                      Marks: 3

                                      Unpolarised light with intensity I0 = 20 W m−2 is incident on the polariser. The analyser is rotated so that the transmission axis is at an angle of 35° compared to the vertical axis of the polariser. 

                                      4-3-5c-question-stem-sl-sq-easy-phy

                                      (c)
                                      Calculate the intensity of the analysed light.
                                      [3]
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                                        Key Concepts
                                        Malus's Law

                                        Question 5d

                                        Marks: 4

                                        Polaroid sunglasses use polarisation to reduce glare.

                                        (d)
                                        Choose suitable words and phrases to complete the following passage:
                                         
                                        When unpolarised light is reflected / refracted from smooth non-metallic surfaces, partial / total plane polarisation occurs. Light is then polarised in a plane perpendicular / parallel to that surface.
                                         
                                        Most surfaces around us are horizontal, therefore, most of the reflected / refracted light is polarised in the vertical / horizontal plane.
                                         
                                        Polaroid sunglasses have a vertical transmission axis, which means that only light oscillating in the vertical / horizontal plane will be transmitted.
                                         
                                        This greatly reduces the glare from reflective / refractive surfaces, such as water, allowing the wearer to see objects beneath the surface of the water more clearly. 
                                        [4] 
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                                          Key Concepts
                                          Malus’s Law