1. 1
   A satellite communications engineer is comparing the transverse electromagnetic waves used in different broadcasting systems. All electromagnetic waves travel at the same speed in a vacuum, but they differ in wavelength and frequency, and this determines how they behave and how hazardous they are.

   (a)

   Which type of electromagnetic wave has the longest wavelength?

   [1 mark]

   • ARadio waves
   • BUltraviolet
   • CX-rays
   • DGamma rays

   (b)

   The engineer notes that as the frequency of an electromagnetic wave increases, its potential to cause harm also increases. Which type of electromagnetic wave carries the greatest potential danger to living cells?

   [1 mark]

   • ARadio waves
   • BMicrowaves
   • CInfrared
   • DGamma rays

   (c)

   State two ways in which all electromagnetic waves are similar, in terms of how they travel and what they transfer.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hospital radiography department uses several types of electromagnetic radiation for different medical purposes: one type to image broken bones, one type to sterilise surgical equipment, and one type in remote controls for adjusting patient bed positions.

   (a)

   Which type of electromagnetic radiation is used to image the internal structure of broken bones?

   [1 mark]

   • AInfrared
   • BUltraviolet
   • CX-rays
   • DRadio waves

   (b)

   Which type of electromagnetic radiation is used by the hospital to sterilise surgical equipment?

   [1 mark]

   • AMicrowaves
   • BGamma rays
   • CVisible light
   • DUltraviolet

   (c)

   A nurse in the department is exposed to x-rays regularly while assisting with imaging. Explain why excessive exposure to x-rays is harmful to the human body.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is investigating why a black metal plate left in direct sunlight becomes noticeably hotter than a shiny silver plate placed next to it, both made of the same metal and exposed to the same sunlight for the same length of time.

   (a)

   Describe, in terms of absorption of electromagnetic radiation, why the black plate becomes hotter than the silver plate.

   [3 marks]

   (b)

   The student then wraps the silver plate in black fabric and repeats the experiment, finding that the wrapped plate now heats up at a similar rate to the original black plate. Explain this result, and suggest one way the student could improve the reliability of their comparison between the two plates.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A mobile phone network company wants to build a new mast that will transmit both radio waves and microwaves to nearby homes for communication purposes. Local residents have raised concerns about possible health effects, having heard that ultraviolet, x-rays and gamma rays can cause cancer.

   (a)

   Explain, using ideas about frequency and energy across the electromagnetic spectrum, whether the residents' concerns about the radio waves and microwaves from the mast are justified.

   [6 marks]

   (b)

   The company also proposes fitting the mast with a small ultraviolet lamp to deter birds from nesting on it, and a technician suggests that this lamp could instead be used to disinfect the mast's water drainage system. Evaluate whether the technician's suggestion to reuse the ultraviolet lamp for water disinfection is a sensible use of that part of the electromagnetic spectrum, and describe one precaution that should be taken when installing it.

   [6 marks]

   Total for question 4: 12 marks

End of questions