3) Waves Flashcards
Define Wave motion:
Wave motion is the transfer of energy from one place to another, without transferring matter.
Define Wavefront:
Wavefront is the imaginary line joining all the crests on a wave.
Define Wavelength:
Wavelength is the distance between two consecutive crests, two consecutive troughs or between any two points in phase.
Define Frequency
Frequency is defined as the number of vibrations passing trough a point per unit time.
Define Transverse wave
A transverse wave ia a wave in which the direction of vibration is at right angles to the direction of propagation . Examples include: electromagnetic radiation, water waves and seismic S-waves (secondary) can be modelled as transverse.
Define Longitudinal wave:
For a longitudinal wave, the direction of vibration is parallel to the direction of propagation . Examples include: sound waves and seismic P-waves (primary) .
Define Refraction
It is the bending of light when light changes media. due to a change of speed
Define Reflection:
It is the bouncing back of waves after hitting a surface.
Define Diffraction:
Diffraction is the spreading of waves around obstacles.
Define Angle of incidence:
It is the angle between the incident ray and the normal.
Define Angle of refection:
It is the angle between the reflected ray and the normal.
Define Normal
A normal is a perpendicular line drawn to a surface , at the exact point where the incident ray hits the surface
Define Plane mirror:
A plane mirror is a mirror with a flat reflecting surface.
Define Critical angle:
Critical angle is that angle of incidence , for which the angle of refraction is 900.
Converging lens
A converging lens is a lens that allows all the parallel rays of light passing through it, to converge at a point.
Diverging lens:
A diverging lens is thinner in the middle than it is at the edges.
Thin lens:
A thin lens is a lens that has a negligible thickness in comparison to the radii of curvature of the lens surfaces.
Virtual image:
A virtual image is an image formed by rays of light that do not actually meet to form that image. A virtual image is formed when diverging rays are extrapolated backwards and does not form a visible projection on a screen
Real image:
A real image is an image formed by rays of light actually meeting at a point to form that image.
Dispersion of light:
The splitting of white light into its constituent colours when it is incident on a prism is called as dispersion of light.
Spectrum:
A band of colours formed as a result of dispersion is called as a spectrum.
Monochromatic light:
The visible light of a single frequency is described as monochromatic.
Electromagnetic spectrum:
An electromagnetic spectrum consists of a range of all types of electromagnetic radiations.
Compressions :
These are high pressure regions on a pressure wave( longitudinal wave)
Rarefactions:
These are low pressure regions on a pressure wave( longitudinal wave).
Crests
The highest point on a wave above the equilibrium
Troughs
The lowest point of a wavebelow equilibrium or rest
wave speed equation
frequency x wavelength
frequency equation
1/ t
does the speed and wavelength increase when going through more dense (shallow)
decreases
normal towards refracted ray
time equation
1 / frequency
does the speed and wavelength increase when going through less dense (deep)
increase
normal away from refeacted
diffraction
if the gap is small the waves are small
characteristics of image formed by a plane mirror
- same size
- same distance
- virtual
- latterally inverted
- upright
characteristics of reflection
- transverse
- electromagnetic
- travel in the speed of light
- travel through vacuum
When does tir happen
angle of incidence is greater than cirtical
the light travels through more dense (shallow)
when can tir be used
- optical fibres
- reflecters
- prismatic periscope
refractuve index and its equation
ratio of a wave in two different mediums. 1/sin c
why does refractive index have no unit
its a ratio
why does refractive index matter
higher the refractive index slower the speed and higher the density
what are the 3 refractive index equations
1) sini/sinr
2) c/v more dense over less dense (shallow over deep)
c can be speed
3) 1/sin(c) snells law
how is tir used in communication
used to transmit information using visibile light or infra red radiation over a long distance due to high frequency of light and infrared
how is tir used in medicine
endoscopes contains 2 bundles of fibres where one set transmits the light into the body cavity and the other is used to return the reflected light from inside back up forming an image on the c=screen.
a laser on the endoscope can be sued to
cauterise blood vessels and carry retinal eye surgery
principal axis
a line which passses through the centre of the lenses
principal focus
the point at which rays of light travellung parrallel to the principal axis intersect the principal axis and converage.
focal length
the distance between the centre length and pricipal focus
if the object is after 2F
real
inverted
smaller
camera
if the object is at 2F
real
inverted
same size
photocopier
if the object is before 2f
real
larger
inverted
projector
if the object is on the same side as the image
virtual
upright
larger
magnifine glass
myopia
near sightness
image infront of the retina
]concave and diverging lens can be used to bring the image on the retina
hypermetropia
far sightness
image behind the retina
convex lens can be used to being the image on the retina
bifocal lenses
when a person suffers with myopia and hypermetropia
monochromatic
ray of one single wavelenegther or frequ=uency
EMS order and frequency, wavelength and energy
Radio waves
micro waves
Infra red
visible light
ultra violet
xy rays
gamma rays
wavelength decreases down
frequency and energy increases down
Radio waves
- medicine
- astronomy
- radio and tv communication
Micro waves
- Satalleites
- Mobile communicaions
- ovens for cooking
- bluetooth
Causes: Internal heating to the body tissue as micro waves can penetrate walls and require reception
Infra red
- Heating or cooking (electrical grill)
- TV remotes
- SHort range communications and Night visions
Causes: Can burn (microwaves cook from the inside based on water and fat molecules infra red takes longer)
Visible light
- Photography
- illumination
- Vision and sight
Causes; Eye damage when exposed to bright light
Ultra violet
- Security devices in airports
- Detecting fake bank notes
- Sterilising water
causes; SKin cancer and eye condition w=by damaging surface cells
X rays
- medical scanningfor broken bones
- security scanning
causes: cancer becausee it can damage DNA cells causing mutations of the cell.
how does X rays operate and what are some protections
X rays pass easily through soft tissue but it is absorvbed by bone and metals
- Lead apron
-COncreat walls
Gamma rays
- Cancer treatment
- STeralization
CAuses: Cancer and DNA Damage
communication satellites used by microwaves
- some satallietes phones use low orbit artificaol satellites
- some sattelite phones and direct broadcast satellite television use geostationary satellites
what relys on the EMS
- mobile phones (microwaves
- bluetooth (radiowaves
- Optical vibres (visible or infrrared)
Difference between analogue and digital
Analogue has a range of values digital consists of 2
benifts of digital
- increased data transmissions
- increased range due to accuracy
- less interference\
- more information can be sent
- processed easily
Can sound travel through a vacuum and does it need a medium
no but it needs a medium
Sound speeds
Solid = 330-350m/s
liquid = 1500m/s
gas = 5000m/s
what is the relation between pitch frequency and amplitude and volume
amplitude is directly to volume
frequemncy is directly to pitch
uses of ultra sound
1) Medicine to getnerate images of organs and remove kindey stones
2) Quality control to check for cracks and air bublles inside metal objects
3) SONAR
4) Cleaning
