Chapter 6 - General waves + sound waves Flashcards
What do waves do
Transfer energy without transferring matter
What are the 2 types of waves
How to particles vibrate
Transverse - Particles vibrate perpendicular to the direction of propagation of the wave.
Longitudinal - Particles vibrate parallel to the direction of propagation of the wave.
How does the wave travel
Longitudinal - compressions and rarefactions
Transverse - crests and troughs.
What is an oscillation
to-and-fro movement of a particle
What is frequency
Unit
Number of waves passing any point per second
Hertz (Hz)
What is wavelength
Distance between 2 consec crests or compressions.
What is amplitude
The maximum displacement of any point in the wave from its rest position.
What is the wave eqn
What is proportional to what
V = F * Lambda
V prop wavelength
F inv prop velocity
Relation between frequency and time
1/time
Where do transverse and longitudinal waves travel
Transverse - Solids and surface of liquids
Longitudinal - can travel through solids, liquids and gasses.
What is time period
Time needed to produce one complete wave.
What is reflection
Travelling back of a wave falling on a surface into the same medium
What is diffraction
The bending of waves around the sides of an obstacle or spreading of waves as they pass through a gap
What is reffraction
The change of direction of waves due to a change in speed of the waves.
When is diffraction significant.
If the size of the gap is comparable to the wavelength.
examples of transverse waves
light, water, seismic S-waves
examples of longitudinal waves
sound waves
what is a transverse wave and properties of them
-Travelling waves in which oscillation is perpendicular
to the direction of travel
-light waves
-Has crests and troughs
what is a longitudinal wave and properties of them
-Traveling waves in which oscillation is parallel to the direction of travel.
-sound waves
-Has compressions and rarefactions
what occurs in refraction from deep-shallow
Speed and wavelength are reduced
frequency stays the same and the wave changes direction
when a wave is slowed down how does it refract
towards the normal
the angle of incidence > angle of refraction
when a wave is sped up how does it refract
away from the normal
angle of incidence < angle of reflection
what happens to waves as they move from deep to shallow water
speed decreases, wavelength decreases
frequency remains constant
what happens to waves as they move from shallow water to deeper water
speed increases, wavelength increases
frequency remains constant
refractive index from rarer to denser
sin i/sin r
refractive index from denser to rarer
sin r/sin i
refractive index formula (general)
speed of light in air/speed of light in medium 2
or c/v
c = speed of light in air = 3 x 10^ m/2
v = speed of light in medium 2
frequency of ultrasound waves
35000 hz
approximate range of hearing of a normal human ear
20Hz to 20kHz
approximate speed of sound in air
340 m/s
Definition of echo
reflection of sound waves
Formula of echo
2d/t
where d = distance travelled
t = time taken
Uses of ultrasound
nondestructive testing of materials
medical scanning of soft tissue
sonar - calculation of depth or distance from time and wave speed
How would a diagram of compressions and rarefactions change if you need to show
higher frequency
louder sounds
frequency:
compressions and rarefactions move closer together
louder - layers (wavefronts) are closer together at C and further apart at R
