Waves Flashcards
What is a wave?
A wave transfers energy (and information) from one point to another without transferring matter
Amplitude
-is half the crest to trough distance. Waves with larger amplitudes carry more energy.
-how far from the equilibrium point the wave has oscillated(vibrated)
Wavelength
Distance of one entire oscillation:
-from one crest to the next crest
-distance between any part of a wave and the next part where the wave starts to repeat itself.
Crest
the highes part of the wave
Throught
lowest point on the wave
Frequency
The number of waves produced in 1 second
Period
Time to make 1 wave
Amplitude symbol and unit?
A
m
Wavelength symbol and unit?
λ
m
Frequency symbol and unit?
f
Hz
Period symbol and unit?
T
s
Transverse waves
Oscillations at right angles, perpendicular to direction of wave motion (energy transfer)
Examples: all electromagnetic waves, water waves, waves of string(guitar)
Longitude waves
Oscillations occur parallel to direction of energy transfer
Example: sound waves
Doppler effect
If a wave source is moving the detected waves will have a different wavelength than if the object was stationary.
-If the wavelength is greater, source moving away
-if wavelength is less, source is moving towards us
-The greater the shift in wavelength the greater the speed of the object.
electromagnetic spectrum
Radio waves
microwaves
Inferred
radiation
Visible light
Ultra violet
x-ray
Gamma rays
electromagnetic spectrum goes from …. wavelength to …… wavelength
and from ….. frequency to …. frequency
1) long
2) short
3) low
4) high
visible spectrum goes from …. wavelength to …… wavelength
and from ….. frequency to …. frequency
1) long
2) short
3) low
4) high
visible spectrum
red
orange
yellow
green
blue
indigo
violet
Similarities of electromagnetic spectrum
- all Transverse waves
- travel at same speed in a vacuum
Law of Reflection:
The angle of incidence = The angle of reflection
ray diagram reflection
-First draw the boundary (like a mirror)
-Then the ray of incidence hitting in to the boundary (mirror) at a certain angle
-Then draw the normal and measure the angle of incidence
-The angle of incidence is the same as the angle of reflection so draw the ngle of reflection on the other side and add the reflected ray
What happens to wave speed during refraction?
-wave speed slows down when it enters a glass block
-waves will have different speeds for different materials
Ray diagram refraction
-First draw the ray of incidence hitting into the glass
-Draw the normal and know that the angle of incidence going from air to glass bends towards the normal
-This new line that was bent towards the normal is called Refracted ray, forming the angle of refraction (from normal to refracted ray)
-Then at the point of refraction on the other side of the glass box draw another normal and bend the ray of refraction away from the normal
Can all waves be reflected and refracted?
yes, transverse and longitude
Total internal reflection
-The critical angle is when the ray of refraction disapears and is 90oC to the normal
-Then the angle of incident becomes the critical angle
if the angle of incidence is bigger then the critical angle then we get total internal reflection
Total internal reflection can only occur when:
- a ray of light travels from a dense material into a less dense material
- the angle of incidence is greater than the critical angle
Sound is an example of a Longitudinal or transverse wave.
longitudinal wave
Range of human hearing
Frequency 20 – 20,000 Hz
decreases with age
Does sound travel faster in liquid solid or gas? why?
In solids because the particles are more densely packed the particles vibrate and collide with each other and the sound waves can get transmitted through material
Can sound travel through vacuum? Why?
No because there are no particles to vibrate and collide the waves can’t get transmitted
as sound speed up wavelength …. and frequency ….
1) increases
2) doesn’t change
wavelength gets ….. as waves speed up (through different densities)
longer
wavelength gets …. as waves slow down (through different densities)
shorter
higher frequency … pitch
higher
amplitude increases volume ……
increases
Displaying sound waves
- We can display sound waves by using a combination of a microphone and oscilloscope.
- The Microphone converts sound energy into electrical energy.
- These electrical signals are then displayed on the oscilloscope screen.
Measuring the Speed of Sound
- We measure the time it takes for us to hear the clapper which is 100 meter away
- We used a clapper, a stopwatch and a trundle wheel
- We measure the quantities by starting the stopwatch when the clapper made contact and stopped the stopwatch when you hear the sound
- We took 8 repeats
- Speed = distant/time
- Use ear protector on the person using the clapper to block the loud sound so it does not damage your ears
