Topic 3: Waves Flashcards
(27 cards)
What happens when white light is shone into a triangular prism?
disperses into colours - different wavelengths are refracted by different amounts
What does refractive index tell you?
how fast light travels in that material
refractive index, speed of light in vacuum and speed of light in material equation
refractive index = speed of light in vacuum/ speed of light in material
What is the speed of light in a vacuum? (refractive index)
1.00
What is Snell’s law?
n = sin(i)/ sin(r)
What is the critical angle?
when the angle of refraction = 90
What happens when the angle of incidence is above the critical angle?
total internal reflection
The higher the refractive index…
the lower the critical angle
How do you work out the critical angle?
Sin C = 1/ n (refractive index)
2 uses of total internal reflection
-optical fibres
-prisms (periscope)
Total internal reflection: prisms (periscope)
-ray of light shines into one prism and is totally internally reflected by 90
-light travels through another prism and is totally internally reflected by 90
-ray is now travelling parallel to its original path
Sounds waves are…
longitudinal
Sound travels fastest in…
denser mediums
What can be used to measure sound waves?
oscilloscope
The greater the amplitude of the wave…
the more energy it carries
The higher the frequency of a sound wave…
the higher the pitch
Transverse waves
vibrations perpendicular to direction of travel
Longitudinal waves
vibrations parallel to direction of travel
Transverse waves examples
-EM
-light
Longitudinal waves examples
-sound
-shock waves (seismic)
Speed, frequency and wavelength equation
speed = frequency x wavelength
What is the doppler effect?
the change in frequency or wavelength of a wave for an observer moving relative to its source
Doppler effect examples
-if a car is moving away from you, the frequency of the wave will be lower
-if a car is moving towards you, the frequency of the wave will be higher
(visible light) Red has the…
longest wavelength and lowest frequency
