Topic 9 Practice Paper: Electromagnetic spectrum — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   Which row lists electromagnetic regions in decreasing wavelength (longest first)?

   	Longest → shortest
   A	gamma, X-rays, ultraviolet, visible
   B	radio, microwaves, infrared, visible
   C	visible, infrared, microwaves, radio
   D	radio, gamma, visible, ultraviolet
2. 2

   In a vacuum, a radio wave and a gamma ray have the same

   1. Awavelength
   2. Bspeed
   3. Cfrequency
   4. Denergy per wave
   ( )
3. 3

   An infrared wave in a vacuum has a wavelength of 9.0 × 10⁻⁷ m. Taking v = 3.0 × 10⁸ m/s, its frequency is

   1. A2.7 × 10² Hz
   2. B3.3 × 10⁻¹⁵ Hz
   3. C3.3 × 10¹⁴ Hz
   4. D2.7 × 10¹⁶ Hz
   ( )
4. 4

   Which application uses ultraviolet radiation?

   1. AChecking a broken bone
   2. BCooking a chicken
   3. CCarrying satellite TV
   4. DSterilising water
   ( )
5. 5

   A security team uses a scanner to inspect closed suitcases without opening them. The region used is

   1. AX-rays
   2. Binfrared
   3. Cradio waves
   4. Dvisible light
   ( )
6. 6

   Excessive exposure to microwaves is harmful because microwaves

   1. Aburn the skin surface
   2. Bcause internal heating of body cells
   3. Cmutate bacteria in the body
   4. Ddamage the retina with light
   ( )
7. 7

   Some satellite phones communicate with low orbit satellites rather than geostationary ones. A geostationary satellite is one that

   1. Aremains fixed in space without orbiting
   2. Borbits very close to the ground
   3. Corbits the Earth once every 24 hours above the equator, staying over one point
   4. Dorbits over the poles
   ( )
8. 8

   Optical fibres carry broadband signals as

   1. Aelectrical currents in copper strands
   2. Bsound pulses in air channels
   3. Cmicrowaves bouncing inside glass
   4. Dpulses of visible light or infrared trapped by total internal reflection
   ( )
9. 9

   An analogue signal differs from a digital signal because it

   1. Avaries continuously between values
   2. Bswitches between on and off only
   3. Ccannot carry sound
   4. Dtravels faster than light
   ( )
10. 10

    A long-distance digital link stays clear where an analogue link degrades, because at each repeater the digital signal is

    1. Aamplified together with its noise
    2. Bregenerated to its clean original pulses
    3. Cconverted into sound and back
    4. Dslowed down to remove noise
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 11

   The electromagnetic spectrum is continuous, but physicists name its main regions.

   1. (a)

      List, in order of increasing frequency, the seven main regions starting with radio waves.

      [2]
   2. (b)

      State how the wavelength changes as the frequency increases.

      [1]
   3. (c)

      State the speed of these waves in a vacuum.

      [1]
   4. (d)

      State one property, other than speed, that is the same for every region.

      [1]
2. 12

   A hospital uses gamma rays, X-rays and ultraviolet lamps for different jobs.

   1. (a)

      State which region is used to sterilise medical equipment, and explain why that region is suitable.

      [2]
   2. (b)

      State which region is used to image a broken leg, and state one hazard of this region to staff.

      [2]
   3. (c)

      Give one use of ultraviolet in daily life and one precaution against its harmful effects.

      [2]
3. 13

   A student’s household has a satellite dish pointed at a geostationary television satellite, a mobile phone, and a Bluetooth speaker.

   1. (a)

      Explain why the satellite dish never needs to be re-aimed.

      [2]
   2. (b)

      Name the region of the spectrum carrying the signal from the satellite to the dish, and the region used by the phone.

      [2]
   3. (c)

      Name the region used by the Bluetooth speaker link.

      [1]
4. 14

   A radio station broadcasts music as an analogue signal on one channel, and as a digitally encoded signal on another. A listener drives into a valley where the signal is weak and pick-up is noisy.

   1. (a)

      Describe the difference between the two signals.

      [2]
   2. (b)

      Explain which broadcast the listener can still hear clearly, and why.

      [2]