Yr 12 - Waves (2 of 2) Flashcards
Order of EM spectrum (starting with largest wavelength & smallest Frequency)
- Radio
- Micro
- Infrared
- Visible
- Ultraviolet
- X-Rays
- Gamma
Wavelengths for each em wave starting with greatest
- Radio 10^5
- Micro 10^-1
- Infrared 10^-3
- Visible 8x10^-7
- Ultraviolet 4x10-7
- X-rays 10^-8
- Gamma 10^-12
All in meters
Frequencies for each em wave starting with the lowest.
- Radio 10^3
- Micro 10^8
- Infrared 10^12
- Visible 10^15
- Ultraviolet 10^16
- X-Rays 10^18
- Gamma 10^20
All in hertz
Which type of waves can be polarised?
Transverse Waves only.
Longitudinal already in 1 plane.
What would a arrow diagram of each wave be like:
- Polarised wave
- Unpolarised
- Arrow pointing in one straight direction only
- Arrows pointing in every direction
Which type of waves used for thermal imagery & by rattlesnakes?
Infrared
Why is there a glare on a large body of water when the sun is shining?
- Light from sun is unpolarised
- When light hits water it is polarised
- Some light is refracted into the water and the rest is reflected off the water.
- Light reflected is polarised & glares due to high intensity in one plane.
What is a plane polarised wave?
A traverse wave oscillating in 1 plane.
What is the refractive index?
Ratio of speed of light in vacuum to speed in a substance.
Describe why a light wave refracts away/to from the normal the moving into a substance.
Less -> more dense
- Towards normal as wave hits substance at an angle and the side of wave that contacts first is slowed and therefore the wave (bends).
More -> less dense
- Away from normal (vice versa)
Think about it as a car going off-road at an angle
What is snells law?
n Sin𝞡 = constant
n sin(AOI) = n sin (AOR)
AOI = Angle of Incidence
AOR = Angle of refraction
Where are AOR & AOI measured from?
Both are measured from the normal
What is total internal reflection & when does it occur (angles)
Reflection of all light back into original medium
- Occurs when AOI is greater than C
- When AOI = C light directed along boundary
C = critical angle
What is an alternative (but similar) equation:
Sin C = 1 / n
Sin C = n2 / n1
What happens when light travels into:
- Lower n
- Higher n
- Faster
- Slower