Definitions
The name of the matter a wave passes through.
Medium.
v = ?
The name of maximally displacing points in a standing wave.
Antinodes.
A sound wave may be categorised as a ___ wave.
Longitudinal.
What does the wavefront pattern look like after plane waves pass through an infinitely small slit?
Semicircles spreading out.
Define refraction.
Wave change speed --> change direction.
Medium, Transverse.
If a wave speeds up, it refracts ___ from the normal.
This is the speed of sound on the data sheet.
340ms^-1 (in room temp air).
Two square waves (+2cm, +3cm sides, i.e. both have positive displacement) approach each other. What do they look like superimposed?
Square snowman 5cm high by 3cm wide (2cm wide top).
The 2 key characteristics defining waves.
Transfers energy without permanently transferring mass.
These 3 are features of a longitudinal wave.
Amplitude, Compression, Rarefaction, Equilibrium, Wavelength, etc. etc.
Decreasing this decreases diffraction.
Wavelength.
Energy naturally expands out in a ___ shape.
Spherical.
Your microwave has wavelength 1cm. Its frequency is:
f = v/L = 3*10^8 / 10^-2 = 3*10^10 Hz
Define equilibrium, and describe where it is in the context of a longitudinal wave.
Most stable configuration/position of particles. Original position of each longi. wave particles.
Explain why in Inception, DiCaprio hears the tracks humming before the rumbling train.
Sound (vibrations) faster in solids. (medium --> wave velocity)
When a wave changes medium, (1) changes, but (2) always stays the same.
Velocity (or Wavelength), Frequency.
A peak of a pressure-position graph has this y-level on a displacement-position graph.
0.
Light is 800nm wavelength in vacuum. It passes into glass and is now 400nm. What is its speed?
1.5*10^8 ms^-1 (freq. constant)
Define standing waves and resonance.
BONUS: What are some situations you can see both?
Standing waves oscillate in place with no net energy transfer. Resonance is driving = natural freq. (max energy transfer) Famously, both resonance and standing waves are seen in string and wind instruments.
Given a displacement-time graph of a sound wave, name 4 variables you can derive.
Amplitude, Period --> Frequency --> Wavelength (knowing v=340ms^-1)
These 4 conditions must be true for two waves to make a standing wave.
Shrek argues if he runs towards Donkey, sound reaches him faster. Puss argues if he screams with more energy, sound goes faster.
Is Shrek wrong? Is Puss wrong?
Both wrong. (medium --> velocity) (energy --> amplitude, frequency)
What is the acceleration of particles on the crest, trough, and equilibrium (ascending & descending) of a transverse wave travelling right to left?
Crest: Max down. Trough: Max up. Both eq. points: 0.