Waves Flashcards
what are transverse waves and eg.
-waves oscillations travel perpendicular to the direction of energy transfer- travel in vacuum
-pass through SOLIDS ONLY
-e.g. ripples in water, s-waves, electromagnetic waves
what are longitudinal waves and eg.
waves oscillations travel parallel to direction of energy transfer
-cant travel in vaccum
- PASS THROUGH SOLIDS/LIQUIDS
- e.g. sound waves
- P-waves
- pressure waves
what is Amplitude , symbol and measured in?
-distance from undisturbed position to peak/trough of wave
symbol : A
measured in : metres
what is wavelength , symbol and measured in?
distance from one point of wave to same point on next wave
symbol : lambda
measured in : metres
what is frequency , symbol and measured in?
no. waves passing a point in a second
symbol : f
measured in : Hz
what is time period , symbol and measured in?
time taken for single wave to pass a point
symbol : T
measured in : seconds
equation for frequency and time period?
f= 1/T
what is wave speed , symbol and measured in?
-distance travelled by a wave each second
symbol : V
measured in : M/S
WAVE SPEED EQUN
wave speed = f x wave length
laws of reflection
1.angle of incidence=angle of reflection
2.incidient ray,reflected ray and normal are all in the same plane
what are the least and best surfaces for reflection
least reflective : ROUGH SURFACES
most reflective : FLAT SURFACES
WHAT IS REFRACTION?
The change of direction in which they travelling when they cross the boundary between 1 medium to another
what is REFLECTION, TRANSMISSION, ABSORBTION ?
1)REFLECTION: light will reflect if object is OPAQUE /not absorbed
- smoother the surface , stronger the reflective wave
2)TRANSMISSION: pass through transparant material
3)ABSORBTION: if frequ of light matches energy levels of electrons - light will be absorbed by electrons and not REEMITTED
how do soundwaves travel in the ear?
1.travels down AUDITORY CANAL
2.pressure of sound waves cause eardrum to VIBRATE
3.small bones connected to this also vibrate and the vibrations transfer to fluid in INNER EAR —> nerve cells detect sound
how does ultrasounds for medicine work?
and how does it image under surfaces?
measure the time between emmison and detection to show distance from source
imaging under surfcaes is done becuase a crack causes WAVES TO REFLECT EARLIER than the rest, so will show up
how are radio waves produced?
produced by oscillations in electrical circuits
- when absorbed, create AC with same FREQUENCY AS RADIO WAVE
hazards of UV, X-RAYS , GAMMA RAYS?
UV = skin ages prematurely ( skin cancer)
X-RAYS/GAMMA RAYS = ionsising radiation causing cancer /gene mutation
INVESTIGATING wave properties
1)Set up a ripple tak with a screen underneath and fill the ripple tank with water to a depth of no more than 1 cm
2)Turn on the power supply and the light source to produce a wave pattern on the screen
3)The wavelength of the waves can be determined by measuring length of several waves and dividing this by no. waves
4)A stopwatch could be used - time for several waves to pass a point
5)Frequency = number of waves/time
Record the frequency and wavelength in a table and repeat the measurements
