Waves Flashcards
What is Phase difference?
the fraction of a cycle (measured in degrees or radians) between the oscillations of two particles
What is Path difference?
the difference in the distances travelled by two waves from coherent sources at a particular point
Principle of superposition (Waves)
when two or more waves meet, the resultant displacement is equal to the sum of the displacements of each wave
Interference
when two waves superpose at a point and there is a change in overall displacement
Displacement
distance moved from equilibrium of a point on a wave
Amplitude
maximum displacement
Wavelength
the distance between two adjacent peaks ‘or’ troughs
Period
the time taken for one complete oscillation of a particle
Frequency
number of wavelengths passing a point per unit time
Plane polarized wave
a transverse wave that vibrates in one plane only
Node
A point on a stationary wave where the amplitude is always zero
Antinode
A point where the amplitude of the standing wave takes the maximum possible value
Coherence
Same frequency and constant phase difference
Monochromatic
Same wavelength
What are the condition required for a stationary wave to form?
Two waves travelling/propagating in opposite directions superpose with the same frequency and similar amplitudes
What is an antinode on a stationary wave?
A point where the progressive waves are in phase and constructively interfering resulting in maximum amplitude
What is an node on a stationary wave?
A point where the progressive waves are in antiphase and are destructively interfering resulting in minimum amplitude
How many wavelengths are there between adjacent nodes of a standing wave?
Half a wavelength
What is the phase difference between points either side of a node?
Pi Rad/180 degrees
What is the phase difference of points between two adjacent nodes?
Zero
How does phase vary along a progressive wave?
Changes continuously across each wave cycle.
How does amplitude vary in a stationary wave?
It varies continuously along the wave. It is a maximum at antinodes and a minimum at nodes
How does amplitude vary in a progressive wave?
It is the same at every point along the wave.
What type of wave doesn’t tranfer energy?
Stationary waves
What is the fundamental frequency of a string?
The lowest frequency which produces a stationary wave on the string.
Why can only certain frequency stationary waves be produced on a stretched string?
here must be nodes at the fixed ends and only certain frequencies/wavelengths allow this.
What is the principle of superposition in waves
When two waves meet at a point the resultant displacement is the (vector) sum of the displacements of the individual waves
What is constructive interference?
When two waves superpose in phase causing an increase amplitude.
What path difference is required for waves to be in phase?
A whole number of wavelengths
What path difference is required for waves to be in antiphase?
An odd number of half wavelengths
What is the relationship between path difference and phase difference for coherent sources?
(Path difference/wavelength) x 2π
What term describes a phase difference of zero between two waves?
In phase
What term describes a phase difference of π radians between two waves?
In antiphase
What is x in the double slit equation (λ = ax/D)?
Fringe seperation
What is D in the double slit equation (λ = ax/D)?
Distance between the double slits and the screen
What is a in the double slit equation (λ = ax/D)?
Distance between the double slits
What did Young’s double slit experiment demonstrate about the nature of light?
That light exhibits wave behaviour.
What name is given to light of a single frequency/wavelength?
Monochromatic
