Section 3 - Waves Flashcards
wavelength λ
distance from one peak to the next
frequency (f)
how many complete waves there are per s (passing a certain point)
measured in Hz (1Hz = 1 wave per second)
amplitude is
height of wave (from rest to crest)
speed (v)
how fast wave goes
period (T)
time in s it takes for one complete wave to pass a point
frequency formula
f = 1/T
wave speed (m/s) formula
frequency (hz) x wavelength (m)
v = f x λ
transverse waves
the vibrations are at 90º to the direction energy is transferred by the wave
/\/\/\/\/\/\/\
examples:
- light and EM waves
- slinky spring
- waves on strings
- ripples in water
longitudinal waves
vibrations are along same direction as the wave transfers energy
lll l l l ll l l l l ll llll l l ll l l lll lllllll ll l l l l ll l l l ll
compressions and rarefactions
exampkes:
- sound and ultrasound
- shock waves
slinzy spring when you push end
what waves transfer
- all transfer energy in direction they are travelling
- can also transfer information
wavefronts
imaginary planes cutting across all waves connecting points on adjacent waves vibrating together
distance between wavefronts is one wavelength
when talking ab waves aproching obstace multiple waves in same direction are referd to as wavelengths
doppler effect
waves produced by a source which is moving will have different wavelength than if source were stationary
frequency of a wave from source moving towards you will be higher and wavelength will be shorter than wave froduced by source and viceversa
EM waves
have different properties and grouped depending on wavelength
transverse
Radio (least frequency and largest wavelength)
Micro-waves
infrared
visible light
uv
xrays
gamma
uses of radio waves
1) communication
- long and short wave
- missing details
uses of microwaves
satellite communication and heating food
*
uses of infrared radiation
heating and monitor temperature *
EM Light
colours depend on wavelength (red, organge yellow green blue indigo violet)
travel through optic fibres (carry data long distances as pulses of light)
pulse of light enters at certain angle and is refracted continiously until it emerges at other end
*
visible light uses
optic cables - (telephone internet and mediacal)
photography
*
uv uses
used in florescent light
*
xrays uses
viewing internal structures
*
gamma uses
steralising medical equipement
streilising food (and keeping it fresh)
how can em be harmful
most em pass thrpugh tissues without being absorbed, but they can also
1) cause heating of cells (micro-waves)
2) cause cancerous mutations in living cells (gamma)
higher freq = more energy = more dangerous
dangers of microwaves
internal heating - microwave ovens must be shielded to prevent this *
infrared dangers
internal heating that can cause skin burns
- protect yourself using insulating materials*