Science

• What are the two different types of waves?

  Longitudinal and transverse
• How does a transverse wave vibrate in relation to its direction of travel?

  It has vibrations at 90º to the direction of travel
• How does a longitudinal wave vibrate in relation to its direction of travel?

  It has vibrations parallel to the direction of travel
• What happens to the direction and wavelength of a wave during refraction?

  There is a change in direction and a change in wavelength due to the change in speed
• What happens to the wavelength during reflection?

  The wavelength does not change during reflection
• What is the relationship between the angle of incidence and the angle of reflection?

  The angle from the normal to the wave when it hits the object is the same as when it is reflected
• How long does it take for geosynchronous and geostationary satellites to orbit?

  Both take 24 hours to orbit
• What is the difference between a geosynchronous satellite and a geostationary satellite?

  A geosynchronous satellite returns to the same point once every 24 hours, while a geostationary satellite stays above the same point at all times
• How many geostationary satellites are required to send messages effectively?

  At least 3 satellites are required
• Why can't signals travel straight from one satellite to another?

  The signal must travel up to the satellite and back to a ground station first
• How can wave speed be calculated?

  Wave speed can be calculated using the formula: Speed (m/s) = distance (m) / time (s)
• What is the alternative formula for wave speed?

  Wave speed = wavelength (m) × frequency (Hz)
• What are the three characteristics used to describe a wave?

  Wavelength, amplitude, and frequency
• What is wavelength?

  Wavelength is the length of one complete wave
• What is amplitude?

  Amplitude is the maximum displacement of a wave
• What is frequency?

  Frequency is the number of waves in 1 second
• In the given example, what are the values for wavelength and amplitude?

  Wavelength = 4 units, Amplitude = 2 units
• What are the characteristics of the electromagnetic spectrum?

  • All parts transfer energy
  • All are transverse waves
  • All travel at the same speed in a vacuum (3 × 10^8 m/s)
  • Different properties and uses
• What is the speed of electromagnetic waves in a vacuum?

  3 × 10^8 m/s
• How does the danger level of electromagnetic waves change with frequency?

  Higher frequency waves tend to have higher danger levels
• How does the optical density of water affect wave speed and wavelength?

  Low optical density (deep water) results in higher speed and longer wavelength, while high optical density (shallow water) results in slower speed and shorter wavelength
• All waves on the EM spectrum are transverse (they all oscillate perpendicular to the direction of travel)
• when the EM waves are in a vacuum, they travel at same speed (3x10 to the power of 8)m/s
• When the EM waves are in different mediums, they travel at different speeds - this leads to refraction (wave changes direction)
• The EM waves are split into 7 sections
• What makes the EM waves different is their wavelength and frequency , they are inversely related (if 1 goes up, 1 goes down)
• From left to right of the EM spectrum table, the frequency increases while the wavelength decreases
• Humans only see visible light in the EM spectrum - which gives humans the ability to see different colours
• The 7 parts of the EM spectrum are Radio Waves, Micro Waves, Infrared, Visible light, Ultra Violet , X-Rays and Gamma ray
• Ultra Violet, X and Gamma rays all are ionising which means they can cause damage to your eyes
• Radio and Micro waves are used in communication
• Gamma rays comes from radioactive decay
• Visible Light, Ultraviolet and X-Rays come from when electrons drop down levels
• Infrared waves are made when bonds holding molecules together vibrate
• When these EM waves come into contact with eachother, they either get:

  Emitted

  Absorbed

  Refracted

  Or all 3
• What type of lenses cause light rays to diverge?

  Concave lenses
• What symbol is used to represent a concave lens in ray diagrams?

  A lens with outwards pointing V shapes at either end
• What is the horizontal line drawn through the middle of the lens called?

  The axis
• What are the focal points in a ray diagram?

  Points on either side of the lens where light rays converge or appear to diverge
• What is another term for the focal point?

  Principal focus