Unit 1 Flashcards
Light
The physical entity that the human organ of vision is sensitive to
Optics
The scientific field that investigates light through the effects of propagation, its interaction with matter, as well as of its creation and detection
Evidence based science
proposes models which are subject to check, to be verified or rejected, until proven otherwise
Principle of Least Action
Light will travel in the easiest route
First optics scientist
Hero of Alexandria
ptolemy
refraction of light, seen by rays of light from eyes
Lucretius
corpuscular nature, light and heat emitted from the sun
Alhazen’s Analysis
Visual discrimination, perception, and conception
Father of Modern Optics
Johannes Kepler, the Keplarian Turn
Newton
light is particle
Huygen
Light is wave
Huygens Principle
Light emits waves, each point that the wave touches, a smaller wave forms in the same direction and speed
Young’s experiment
Light is a wave. Interference
Michelson
Light is an electromagnetic wave
What causes lights in electrons
electrons changing positions
Black Body Radiation
Absorbs all light, can emit it just as easily, no UV catastrophe
Photoelectric Effect
something wrong with EM theory
Quantum energy
Not continuous, = h x v
Planck’s Constant
h=6.626 x 10^-34 JoulexSec
1eV =
1.6x10^-19 Joule
Charge of en electron
1 eV or 1.6x10^19 Joule
When incoming light hits medium, emitted light is
not faster, electrons not faster, but you can have more
Photoelectric effect
also called photoemission. production of electrons or other free carriers when light is shone onto a material. No emission with red. Electrons are emitted instantly, even with light with small wavelength (blue). Increase in intensity is related to increase in the number of ejected electrons, but not to their kinnetic energy. Speed increase only with larger frequency. KE in linear relation to light freq
Energy of Photon
E=h x v. h=planck’s 6.626x10^-34, v=frequency
Wave
Matter duality. Any wave is also a particle , any particle is also wave.
Photon properties
Energy, momentum, wavelength, frequency. The photon is also a wave
The experimental evidence for the nature of the light converge in that the nature that dominates between corpuscle and wave is:
both
What types of waves are there?
transverse and longitudinal, cannot be both, one or the other
What must the equation have for it to be a wave?
time and space
wave equation
y=y(z,t)=y(vxt-z)
scalar
magnitude only
vector
magnitude and direction
electric field
a distribution of electric field intensity. Force on a unit charge
Electromagnetic field
interdependent, non-static electric and magnetic fields
Electric field and magnetic field orientation
ALWAYS perpendicular to each other. S(direction of propagation)=electric field X Magnetic field
What is the simplest wave?
harmonic
wave equations must have?
time and space
Frequency (v)
determined by the source, DOES NOT CHANGE
Wavelength (lambda)
from peak to peak or trough to trough
Phase
The internal clock of the disturbance
Wavevector
Expresses the rate of phase propagation, similar to wavelength but it is vector
Field intesity
E, scalar
Apmlitude
The max of the field intensity. highest, vector.
What does not change as an electromagnetic wave propagates?
frequency
IR light
fields
UV light
fluorescence
speed of light?
3x10^8. c=v x wavelength
to find the speed of light in any other medium what is dependent?
wavelength, it will always be less than the speed of light
refractive index
speed/speed, unitless. always greater than 1. Dependent on material properties and wavelength
refractive index for water
1.333
what is the speed of light in a medium with refractive index n=2?
3x10^8/2=1.5x10^8
When talking about refractive index, what is important to always mention?
the material
Optical path length
multiply by refractive index if going through medium, will be longer than the actual path traveled.
higher refractive index…
thinner lens
1 rad
360/2pi degrees=57.3 degrees
1 degree
0.0175 rad, 1/360 of circle
1 arcminute
1/60 degree
1 arcsecond
1/60 minute
the line at 20/20
separated by one arcminute
radian
measure the angle from a 1D line from a 2D space
Steradian
angular area of a 2D surface about a 3d space. arc/radius
radiometry
scientific, quantifies radiation across the EM spectrum, employs physical constants
photometry
eye, quantifies radiation in the visible, weighted to human eye resonse
measurement of light with physical terms
actinometry, radiometry
measurement of light considering vision
photometry, chromatometry
units of energy
Joule
Units of Power
energy/time. Watts, 1W = 1 J/s
Units of power density
Power/surface area, W/m^2
Radiometric Quantities
Radiant Power (W), Power per unit surface area (W/m^2), Power per unit solid angle (W/sr), Power per unit surface area and per unit solid angle (W/m^2-sr)
Photometric Quantities
Luminant Power (Lumen), Power per unit area (Lux), Power per unit solid angle (Candela), Power per unit area [surface] and per unit solid angle (Nit)
Nature of waves
Spread out in space (diffraction) and can pass through obstacles and may be added with other waves (superposition)
Nature of particles
Move in a straight line due to inertia, unless a force is exerted upon them.
Rays
A physical entity that does not exist. When passing through a small aperture continue their trajectory without any change. Idealized model of light that corresponds to the direction of propagation
for a wave to exist..
must be subjected to a disturbance.
what waves do not require a medium?
gravatational and electromagnetic. can propagate in vacuum
in what type of fields can forces be exerted
dynamic
unit of frequency
Hertz
angular frequency
w=2pi x v
What units do we use for wavelength in respect to light?
micrometers and nanometers
visible light spectrum
4.3x10^14 Hz (red) to 5.7x10^14 (blue)
in relation to the visible, the UV frequencies are
larger
spherical wave
wavefronts are spherical, a succession of concentric spheres centered on the source
Plane Wave
wave fronts are parallel planes and rays are collimated
converging rays
spherical
What’s the difference between geometric optics and wave optics in reference to light passing through the aperture?
In geometric optics, light does not diverge, creating a shadow. In wave optics, then according to Huygens rule, a source of secondary waves, which results in a diffraction distribution pattern.
what is the smallest quantic entity in which we can slice a light wave?
Photons
What is the key feature of the photon?
energy, which is proportional to its frequency
the experimental evidence for the nature of light shows that the dominant nature is:
both
rectilinear
light rays propagate in straight paths
penumbra
created if the light source is not a point, much smaller than the object. Makes silhouette of shade not so clear
transparency
physical property of a medium that allows light to transcend it. It is a measure of the percentage of light, of specific wavelength range, that transcends through this medium. No absolute transparency. dependent on the medium’s properties, as well as on the wavelength of the electromagnetic wave
dielectrics
optical media in which light can propagate
opacity
opposite of transparency
transluscency
prevents perception of distinct images behind it. frosted glass. diffusion
What does optical media do to light?
slows it down. the larger the refractive index, the slower light propagates through it.
index of refraction
= c/u
what is the range of RI of glass?
1.4-1.9
how are wavelength and refractive index related?
inversely
what range of energies does a photon correspond to in the visible light range?
1.65 and 3.1 eV
microwaves
1mm-3cm. photon energies of 0.00001 to 0.001 eV
radiowaves
few cm to hundreds of meters. long antennas.
Infrared
few micrometers to mm. heat or thermal radiation, higher temp, more infrared
Ultraviolet radiation
300nm to a few nm. 3.5-124 eV Radiation in the 300nm range can cause biological tissue damage
Xrays
photoionization. few nm to 0.000001nm
gamma rays
high frequency EM radiation. small wavelength. 100keV wavelengths less than 10pm.
Isotropic
a theoretical source that radiates evenly to all directions. Point source should be less than 1/10 of the observation distance.
