Waves 1 Flashcards
What is a progressive wave?
An oscillation that travels whilst transferring energy from one place to another without moving matter
Explain the movement of particles when a wave passes through it.
Displaced from equilibrium position to new position - displaces near-by particles - these exert restoring force that moves origional particle to equilibrium
What direction of partilces move in transverse waves?
Perpendicular
Describe properties of transverse and logitudinal waves.
Trasverse - Energy is perpendicular, peaks and troughs
Logitudinal - Energy is parallel, refractions and compressions
What is the definition of displacement?
Distance in a direction. (m)
What is the defintion of amplitude?
The max displacement of the wave. (m)
What is the defintion of wavelength?
The minimum distance betweem adjacent in-phase points. (m)
What is the definition of period of oscillation?
Time taken to complete one oscillation. (s)
What is the definition of frequency?
The number of oscillations that pass through a certain point per time. (Hz)
What is the definition of wave speed?
The distance travelled by a wave per time. (m/s)
What graph represents a wave profile? What can you find with one?
Displacement-distance graph.
Ampitude and wavelength
What properties can you find with a displacement-time graph?
Period and amplitude.
What is the defintion of phase difference?
The difference in displacements of partciles along a wave.
If two partciles have zero phase difference, what are the points known as?
In-phase
How much of a wavelength is 2pie radians?
Whole wavelength.
If particles are in antiphase what does this mean?
Particles are in opposite oscillating patterns.
Draw a displacement-distance and displacement-time graph to remind yourself.
Check online
What happens when a wave relfects?
Wave changes direction at a boundary of two media, remaining in the original one.
What is the Law of Reflection?
Angle of incidence = Angle of reflection
How do we represent wave movements? How are the rays drawn?
Using wavefronts (peak of each wave).
Rays are drawn perpendicular.
What else happens when a wave refracts?
Partial reflection.
If the wave slows down, what way does the wave refract?
Refracts towards the normal
Does refraction affect frequency?
No
Does refraction affect wavelength?
Yes, as speed changes
What happens when a wave enters deep water?
Wave speeds up, refract away from normal, wavelength increases.
Name what these symbols stand for.
n,c,v
n = refractive index
c = speed of light in vacuum
v = speed of light in medium
What is snell’s Law?
n1sin1 = n2sin2
Where is the refractive index 1?
Air and vacuum.
Why cant light microscopes go into too much detail?
Light diffracts so smaller components cannot be seen
What is diffraction? What properties does it effect?
When a wave passes through a gap or around an object.
None. Speed, wavelength, frequency remain the same.
When is diffraction the greatest?
When the size of the gap or object is similar to the wavelength.
What is the reflection of sound waves?
Echos
What does it mean if a wave is polarised?
Particles oscillate on the plane of oscillation, in one direction only.
What does plane polarised mean?
A wave that has been polarised.
If ploarising filters are at 90 degrees….?
Stops all waves from passing through.
Are all waves polarised?
No. Natual waves are usually not polarised.
Why can longitudinal waves be plane polarised?
The oscillations are parallel. ??
What does it mean if a wave is partially polarised and when can this happen?
Most poarticles are oscillating in one plane, but few in others.
When reflecting off a surface.
Give one use of polarising filters?
Sunglasses to stop glare frm surfaces such as lakes.
What happens to intensity as a wave progresses?
Decreases.
How does power spread as a wave progresses?
Uniformly in all directions. Sphere.
What is intensity directly and
inversely proportional to?
amplitude squared
area
What formula means that if we double the amplitude, the intensity will quadruple?
Intensity = (amplitude)^2
Explain what happens to kinetic energy when we drop smth in water.
Half amplitude, half speed, quator kinetic energy
How fast do EM waves travel?
Speed of light in a vacuum.
What EM waves do and dont ionise?
DO NOT - radiowaves, microwaves, infrared and visible light
DO - ultraviolet, x-rays, gamma
Why cant all EM waves realise ionising radiation?
Not enough photon energy to remove electrons frm their shells ??
Explain 3 types of ultraviolet light
WRITEEEEE
What is the refractive Index for refractive glass?
1.5
Why do diamond sparkle? What is its refractive index?
Total Internal Reflection. One of the highest refractive index of all natural materials.
What are the conditions for TIR?
- n1 > n2
- Incident angle > critical angle
What is the critical angle?
The angle and which the refracted angle is at 90 degrees.
The greater the refractive index…?
the lower the critical angle
State and explain the expression for TIR.
n1sin1 = n2sin2
n1sinC = n2sin90
n1sinC = n2
SinC = n2/n1
By using TIR, how can we find the refractive index of a media?
Find the critical angle, know one of the refractive index and use formula.
List the EM waves in order.
Radio, Microwave, Infrared, visible light, ultraviolet, x-rays, gamma rays.
Give all info on radiowaves.
Check
Give all info on Microwaves.
Check
Give all info on visible light.
Check
Give all info on ultraviolet.
Check
Give all info on gamma rays.
Check
Give all info on gamma rays.
Check
If a wave is entering a medium of lower refractive index, where does it refract?
Wave speeds up, refract away from normal.
Inverse proportion from n =c/v
