1. 1
   A navigation buoy at sea emits a sound signal from a fog horn with a frequency of 250 Hz. The sound travels through the air at a speed of 340 m/s to reach a passing ship.

   (a)

   What type of wave is the sound wave produced by the buoy's fog horn?

   [1 mark]

   • ALongitudinal, because the air particles vibrate parallel to the direction the wave travels
   • BTransverse, because the air particles vibrate perpendicular to the direction the wave travels
   • CLongitudinal, because the wave carries matter along with it
   • DTransverse, because the wave has no frequency

   (b)

   Calculate the wavelength of the sound wave produced by the fog horn.

   [1 mark]

   • A1.36 m
   • B85 000 m
   • C0.735 m
   • D590 m

   (c)

   As the ship approaches the buoy, explain how the frequency and wavelength of the sound heard by the crew change, compared with the values measured when the ship is stationary relative to the buoy.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hospital's radiography department uses electromagnetic radiation to produce images of a patient's skeleton for a doctor to examine. The radiographer must select radiation with a very short wavelength and high frequency so that it can penetrate soft tissue but be partly absorbed by denser bone.

   (a)

   Which type of electromagnetic radiation is most suitable for the hospital's equipment, given that it must penetrate soft tissue to reveal the structure of bones?

   [1 mark]

   • AInfrared radiation
   • BRadio waves
   • CX-rays
   • DUltraviolet radiation

   (b)

   Compared with visible light, how do the wavelength and frequency of the radiation used in the imaging equipment compare?

   [1 mark]

   • AThe same wavelength but a higher frequency
   • BLonger wavelength and lower frequency
   • CShorter wavelength and lower frequency
   • DShorter wavelength and higher frequency

   (c)

   Describe one detrimental effect on the human body of excessive exposure to the type of radiation used in this imaging equipment, and describe one precaution the radiographer should take to reduce their own exposure.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Astronomers analysing light from a distant galaxy compare its measured frequency and wavelength with the frequency and wavelength the same light would have if emitted by a stationary source in a laboratory on Earth.

   (a)

   A distant galaxy emits light that is detected on Earth with a lower frequency and longer wavelength than the same light would have if the galaxy were stationary relative to Earth. Explain, in terms of relative motion, why this change in frequency and wavelength occurs.

   [3 marks]

   (b)

   State the order of the electromagnetic spectrum from radio waves to gamma rays in terms of increasing frequency and decreasing wavelength, and explain why all types of electromagnetic radiation, including the light from the distant galaxy, travel at the same speed in free space.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A telecommunications company is planning to expand its network, using radio waves for broadcasting, microwaves for satellite communication, and infrared for a new remote-control system, while a separate medical partner wishes to use ultraviolet lamps to sterilise equipment and gamma rays to sterilise single-use medical instruments.

   (a)

   Describe a suitable everyday or scientific use for each of these five types of electromagnetic radiation, explaining a property of each radiation that makes it appropriate for that use.

   [6 marks]

   (b)

   For three of the electromagnetic radiations described (microwaves, ultraviolet and gamma rays), explain a detrimental effect that excessive exposure could have on the human body, and describe a protective measure that could be taken against each.

   [6 marks]

   Total for question 4: 12 marks

End of questions