Characteristics of Waves Flashcards
(18 cards)
What do all waves have in common?
All waves can refract and reflect. Also Diffract.
What is the definition of Reflection?
Reflection occurs when a wave changes direction at a boundary between 2 different media, remaining in the original medium.
What does the law of reflection state?
The angle of incidence is equal to the angle of reflection.
What is the definition of Refraction?
The change in direction of a wave as it changes speed when it passes from one medium to another.
Do any properties of the wave change in refraction or reflection?
In reflection nothing changes.
In refraction the wavelength changes.
If the wave slows down, its wavelength decreases.
If the wave speeds up, its wavelength increases.
How does refraction differ in water waves?
When a water wave enters shallower water, it slows down and the wavelength gets shorter.
Vice Versa.
What is the definition of Refraction?
Diffraction is a property unique to waves. When waves pass through a gap or travel around an obstacle, they spread out.
Do all properties of a wave stay the same when they diffract?
Yes.
What has an effect on how much a wave diffracts?
The size of the gap the wave passes through. If the size of the gap is similar or equal to the size of the waves wavelength then the wave would diffract more.
What is the definition of Polarisation?
Polarisation means that the particles oscillate along one direction only which means that the wave is confined to a single plane. Limited to one plane perpendicular to the direction of travel.
What is the definition of a plane polarised wave?
A plane polarised wave is a wave in which the oscillations are in one direction only. Limited to one plane perpendicular to the direction of travel.
What is an unpolarised wave?
A wave which has oscillations in several directions.
What type of wave cannot be plane polarised?
Longitudinal Waves as the oscillations are always parallel to the direction of energy transfer. As their oscillations are already limited to one plane.
What is meant by partial polarisation?
When transverse waves reflect off a surface they become partially polarised. This means there are more waves oscillating in one particular plane but the wave is not completely plane polarised.
What is the definition of Intensity?
The intensity of a progressive wave is defined as the radiant power passing through a surface per unit area.
Intensity = Power/Area Units=Wm-2
What type of relationship does intensity have with distance?
An inverse square relationship.
If the distance doubled the intensity will decrease by a factor of 4 as 2 squared is 4.
So if the distance increases by a factor of 100 then intensity will decrease by a factor of 10,000 as it is 100 squared.
What type of relationship does intensity have with amplitude?
Intensity is directly proportional to Amplitude squared.
Double the amplitude and the Intensity will quadruple.
What is the definition of Total Internal Reflection?
Total internal reflection is the complete reflection of a light ray at the boundary between two media, when:
The light is travelling from a more optically dense medium to a less optically dense medium. The angle of incidence is greater than the critical angle for the boundary.
