WAVES (PART 2) Flashcards
- How is an expression for a Wave given?
- ω = angular frequency
- positive sign = the wave moves towards the
left
= this is a negative x direction - negative sign = the wave moves towards the
right
= this is the positive x direction - A = wave amplitude
- k = wave number
- How is the wave number (k) calculated?
k = 2π / λ
- How is the Angular Frequency (ω) calculated?
- ω = 2 . π . f
- What is the phase of the wave?
- the argument of the cosine function
- How can we vary the phase in the expression?
- we can change the point under the observation
- this means that we change the x value
- we can change the time at which a particular point is
observed - we do this by changing the t value
- What happens when two waves of the same type meet and overlap?
- type = frequency
- the waves will superpose
- a new oscillation will be created
- Which kinds of sound waves give rise to easily observed interference effects.
Interference effects are shared points where both the waves pass through.
- two sound waves
- each of the same frequency and the same wavelength
- When are two waves said to be in phase?
- when the crest of one wave falls on the crest of the
other - these waves are identical
- What happens when waves are in phase?
- the waves reinforce each other
- they give rise to a high intensity at the point where the
one crest of the wave falls onto the other - this is known as a COMPLETE CONSTRUCTIVE
INTERFERENCE
- What will cause two waves to cancel each other out?
- the crest of one wave falling on the trough of the
other wave - these waves are identical
- this is known as COMPLETE DESTRUCTIVE
INTERFERENCE
- What happens during Complete Destructive Interference?
- there will be no sound heard at the point where
the two waves cross one another - these waves are 180° out of phase
- What are Intermediate effects in terms of Destructive Interference?
- this is when two waves are neither in phase
- nor are they 180° out of phase
- these waves have a fixed relationship in between
- Destructive interferences and constructive interferences consist of identical waves.
What does this entail?
- they have the same amplitude
- they have the same frequency
- they have the same amplitude
- What produces alterations of maximum and minimum intensity?
- they are produced by the superposition of two waves
- these two waves have slightly different frequencies
- these frequencies are known as beats
- What are beats?
- they are the oscillations in the amplitude
- they are found in a superimposition wave
- they express the loudness of the sound
- What are 2 important frequencies with regards to waves created by the superimposition of two non-identical waves?
FREQUENCY ONE:
- this is the actual frequency of the resulting disturbance
- this is known as the Carrier Frequency
FREQUENCY TWO:
- this is the frequency with which the maximum
amplitude of the superimposition wave changes
- What happens to waves that have a fixed attachment point?
WHEN THE STRING IS NOT ABLE TO MOVE AT THE POINT OF ATTACHMENT:
- the reflected wave is inverted
- it travels back along side the strong
- it travels upside down
- the wave is equal in magnitude
- it is always in opposite direction at the attachment
point
- What happens to waves that have an attachment point that is not fixed?
WHEN THE ATTACHMENT POINT IS NOT FIXED:
- the reflected pulse travels back
- it travels back along the wave
- it has the same orientation as the incoming wave
- the incoming and reflected waves will superimpose
- they do this at the attachment point
THESE WAVES:
- have twice the magnitude of the incoming wave on its
own
- What are Standing Waves formed by?
- they are formed by multiple reflections between two barriers
- What does the Green Waveform represent?
- it represents the Standing Wave
- this results from the counter propagating waves
- What happens to the peaks of the Standing Waves (Green Waves)?
- they do not propagate left or right
- they only oscillate up and down
- this is why they are known as Standing Waves
