P5.2

• What are the dangers of ultraviolet radiation?

  • Can cause sunburn
  • Can damage DNA in skin cells, potentially leading to cancer
  • Can cause cataracts, making corneas cloudy
• What do radiographers do to reduce their exposure to radiation?

  They stand behind shielding when operating X-ray machines.
• What are the uses of radio waves?

  • Radio transmission
  • Television transmission
• What are the uses of microwaves?

  • Mobile phones, WiFi, and Bluetooth
  • Cooking food
  • Satellite communications
• How do microwave ovens heat food?

  They heat fat and water in the outer layers, conducting heat to the rest.
• Why are microwaves effective for satellite communication?

  Because they can pass through the atmosphere.
• What are the uses of infrared radiation?

  • Remote controls
  • Optical fibres for broadband
  • Cooking food
  • Heating in radiators
• What are lasers used for?

  Lasers are used to read CDs, DVDs, and Blu-Ray discs.
• How does ultraviolet radiation help in forensics?

  It can detect forgeries by making bodily fluids glow.
• What are the uses of X-rays?

  • Imaging bones
  • Imaging luggage for dangerous substances
• What are the uses of gamma rays?

  • Sterilising medical equipment
  • Killing bacteria on food
  • Radiotherapy for cancer treatment
• What is the electromagnetic spectrum?

  • A continuous spectrum of seven different types of electromagnetic waves
  • All travel at the same speed, $3 \times 10^{8} \text{ m/s}$ in a vacuum
  • All are transverse waves
• How many types of electromagnetic waves are there?

  There are seven types of electromagnetic waves.
• How do the electric and magnetic fields behave in electromagnetic waves?

  They oscillate perpendicular to each other.
• What is the relationship between wavelength and frequency in electromagnetic waves?

  As wavelength increases, frequency decreases.
• Run, Me, Infinite, Vbux, Until, Xylaphones, Gargle (list the seven electromagnetic waves)

  Radio, Microwaves, Infrared, Visible light, ultra-Violet, X-rays, Gamma
• What is Visible Lights use?

  It allows humans to see colour.
• What is an electromagnetic wave?

  An electromagnetic wave are waves that are created as a result of vibrations between an electric field and a magnetic field
• What is a transverse wave?

  A wave that moves in a direction perpendicular to the way in which the particles are vibrating
• What is a longitudinal wave?

  A longitudinal wave is a wave in which the particles of the medium vibrate parallel to the direction of wave propagation.
• What is a period?

  the interval of time it takes for a motion to repeat
• What is a frequency?

  the number of waves that pass a fixed point in unit time
• What is reflection?

  when a wave changes direction at the boundary between two different mediums
• What is refraction?

  the change in direction of a wave passing from one medium to another caused by its change in speed
• What are the two things you need to measure the speed of sound waves using a wall?

  Stand far away and clap
• What two pieces of equipment are needed to measure the speed of sound waves?

  Stopwatch and ruler
• What equation would you use to work out the speed of sound waves?

  Speed = frequency × wavelength
• What does the term 'wave velocity' refer to?

  The speed at which a wave travels through a medium
• What is 'frequency' in the context of waves?

  The number of waves that pass a point in one second
• What does 'wavelength' refer to in wave behavior?

  The distance between two consecutive wave peaks
• What are the keywords associated with a longitudinal wave?

  Compression, Rarefaction, Wavelength
• What is the process to measure the speed of sound?

  1. Make a distinct clap in front of a wall.
  2. Record the time taken between the sound and the echo.
  3. Halve the recorded time to account for the sound traveling to the wall and back.
  4. Measure the distance to the wall.
  5. Use the equation: speed = $\frac{distance}{time}$
• What is the equation to calculate speed?

  speed = $\frac{distance}{time}$
• Why do you halve the time recorded when measuring the speed of sound?

  To account for the time taken for sound to travel to the wall and back
• What is the first step in measuring the speed of sound?

  Make a distinct clap in front of a wall
• If the time taken for the sound to echo back is 4 seconds, what is the time to the wall?

  2 seconds
• What do you need to measure to find the speed of sound?

  The distance to the wall and the time taken for the echo
• What does the term 'compression' refer to in a longitudinal wave?

  It refers to the region where particles are closest together
• What does the term 'rarefaction' refer to in a longitudinal wave?

  It refers to the region where particles are farthest apart
• Two pieces of equipment needed to measure waves in a tray

  A ruler and stopwatch