Waves Flashcards
(23 cards)
How are stationary waves formed?
When two waves (with the same frequency, wavelength and amplitude) travel in opposite directions to each other and superpose with each other.
What is an anti-node?
A point on a stationary wave with maximum amplitude
What is a node?
A point on a stationary wave with no amplitude
What is a harmonic?
The specific frequencies that result in stationary waves being formed
What is the fundamental frequency?
The lowest frequency that produces a stationary wave
What is the amplitude of a wave?
A wave’s maximum displacement from its equilibrium position
What is coherence?
Two or more waves that have a constant phase difference (and frequency)
What is constructive interference?
When the individual displacements of two waves act in the same direction, resulting in a larger resultant displacement.
What is destructive interference?
When the individual displacements of two waves act in opposite directions, resulting in a smaller resultant displacement.
What is the critical angle?
The angle of incidence that results in an angle of refraction of 90 degrees
What is diffraction?
The spreading out of waves as they pass through a gap or around objects
What is intensity proportional to?
Amplitude^2
What is interference?
The superposition of waves when they meet
When does maximum diffraction occur?
When the slit gap is similar length to the wavelength of the wave
What is the principle of superposition?
When two waves meet at a point, the resultant displacement is equal to the sum of displacements of the individual waves at that point.
What are the two conditions for total internal reflection?
When the light is travelling from a higher refractive index to a lower refractive index
Angle of incidence must be above the critical angle
What is plane polarisation?
When a transverse’s wave oscillations are restricted to one component only
What is phase difference?
How far out of sync two points are in their wave cycle
Will a sound wave speed up or slow down in a denser material?
Speed up
Will EM waves speed up or slow down in a denser material?
Slow down
How can polarisation of visible light be demonstrated?
Hold two polarising filters together
Rotating one of them will change the intensity
How can you determine if a source of visible light is polarised?
Hold a polarising filter up to the source
Rotating it will cause a change in intensity
How can you determine the intensity of light from a point source?
P/4PiR^2
