Definition of a Wave- Disturbance caused by a source which transfers energy
In this unit, we studied different properties of waves, and how they interact with each other and other boundaries
In this unit, we studied different properties of waves, and how they interact with each other and other boundaries
Wave Investigations
Different Types of Waves
Mechanical Waves vs. Electromagnetic Waves
- Transverse waves- Oscillation is perpendicular to direction of motion (rope wave, light)
- Longitudinal waves- Oscillation is parallel to direction of motion (sound waves, pressure waves)
Mechanical Waves vs. Electromagnetic Waves
- Mechanical Waves- Require a medium (ocean, sound)
- Electromagnetic Waves- Don't require a medium (light, radio)
- We aren't studying these
- Example: When there is an explosion on the moon, you see the light (travels through space) but you don't hear the sound (can't travel through space)
Wave Speed
- Wave velocity depends on the medium!! It is not affected by wave energy
- Waves travel at a constant speed
- If you double frequency, then wavelength must be cut in half to maintain a constant speed
- Triple the period - Triple the wavelength
Wave Properties
Different Parts of Waves
- Amplitude- Maximum displacement of oscillations in a wave
- Transverse- Maximum distance from equilibrium
- Longitudinal- Density of compression
- Amplitude determines the energy the wave carries = greater amplitude, greater energy
- Period- Time between oscillations (seconds)
- Frequency- Number of oscillations per unit of time
- Frequency = 1 / Period
- Wavelength- Distance between waves ( λ)
- Transverse- Distance between crests or troughs
- Longitudinal- Distance between compressions/rarefactions
This video is helpful for visualizing the different properties of a wave and understanding how they interact with each other. |
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Superposition of Waves
Example: Sound of a siren gets higher as the ambulance gets closer, and then lower as the ambulance drives away Example: Red shift = pictures on the Hubble telescope looked more red because the stars are moving away from Earth |
Beats- Changes in amplitude when there are two waves with similar frequencies
Since the waves are not in phase with each other, there are times when there is total destructive interference, so there is no amplitude and therefore no volume
Beat frequency = | f1- f2 |
Since the waves are not in phase with each other, there are times when there is total destructive interference, so there is no amplitude and therefore no volume
Beat frequency = | f1- f2 |
Medium Boundaries
- Where the wave ends depends on the boundaries of the medium
- Fixed on both ends- Wave ends on nodes on both sides (string instrument)
- One open end- One node, one antinode (tuba)
- Two open ends- Two antinodes (flute)
- Ruben's tube: Sound is a longitudinal wave (high density and low density areas), and the areas of high pressure push the flammable gas out more, so it looks like a transverse wave
Standing Waves
Standing Waves- Waves that appear to stand still but there are actually made up of traveling waves that are reflecting and interfering with each other
Nodes- Areas that aren't moving (total destructive interference)
Antinodes- Areas that move the most (total constructive interference)
Nodes- Areas that aren't moving (total destructive interference)
Antinodes- Areas that move the most (total constructive interference)
- Fundamental frequency- Frequency of the simplest possible standing wave
- Harmonics- Integers of the fundamental frequency
Wavelength of a standing wave is determined by the boundary (L) and the frequency
Speed of Standing Waves
This equation shows the relationship between wave speed and the medium for a string. If tension increases, velocity increases. On the other hand, if linear density increases, velocity decreases |
Mechanical Waves Video Notes.pdf | |
File Size: | 2622 kb |
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