Waves Flashcards
What are longitudinal waves?
Waves where the oscillations are parallel to the direction of travel
What are mechanical waves?
Waves that travel through a substance
What are transverse waves?
Waves where the oscillations are perpendicular to the direction of travel
What is polarisation?
When a transverse wave’s oscillations remain in one plane
How do you polarise something?
Direct the wave at a slit, so only the vibrations parallel to the slit pass through.
What is displacement on a wave?
The distance from the equilibrium position
What is the amplitude of a wave?
The point of maximum displacement, it can be measured as the distance from rest to crest
what is the wavelength of a wave?
The distance between to waves, measured from the same point on each wave, for example trough to trough
What is the period of a wave?
The time it takes for one cycle to pass a fixed point
What is the frequency of a wave?
The number of complete waves passing a point in one second
What is phase difference?
The fraction of a cycle between the vibrations of two particles.
What is phase difference measured in?
Degrees or Radians
When does diffraction occur?
When a wave spreads out after going through a gap or round an obstacle
When is diffraction increased?
When the gap is narrower and the wavelength is bigger the waves spread out more
What is superposition?
When waves meet and combine for a brief period of time until they seperate again
What is the new displacement when two waves superpose?
The combined sum of the displacement of the two waves at that point
what happens when two crests meet and two troughs meet?
Supercrests and supertroughs are formed
What happens when a crest meets a trough?
A displacement of zero occurs as the waves cancel each other out
What is a coherent wave?
Waves with a constant phase difference and frequency
How do stationary waves form?
When two coherent waves travelling in opposite directions meet and superpose
What is a node?
A point of no displacement
What is the fundamental frequency?
A stationary wave where it is half a wavelength long and has 2 nodes, one at each end
What. Is an antinode?
A point of maximum displacement
Do stationary waves or progressive waves transfer energy?
Progressive
When the waves are in phase, what does the stationary wave look like?
It superposes to form a large wave as constructive interference takes place
When the waves are out of phase, what does the stationary wave look like?
The waves cancel each other out, destructive interference.
How can you alter the pitch of a note?
To lower - lower the tension of the string or increase the length of the string
