concept 4d Flashcards
electromagnetic spectrum types of light
spectrum of light waves
radio waves at one end (long wavelength, low frequency, low energy)
gamma rays at the other end (short wavelength, high frequency, high energy)
and in-between (from highest to lowest energy) is microwaves, infrared, visible light, ultraviolet, and x-rays
visible is what we see b/w 400 nm and 700 nm
radio waves
very long wavelength
electromagnetic radiation
low frequency, low energy
microwaves
long wavelength electromagnetic radiation
capable of inducing vibration in bonds
infrared
region of electromagnetic spectrum that is not visible
may be perceived as heat
visible light
light that is visible to the human eye
400 nm to 700 nm wavelength
responsible for the colors we see ROY G BIV (red, orange, yellow, green, blue, indigo, violet)
ultraviolet
region of electromagnetic spectrum that is not visible
primarily responsible for the damaging effects of sunlight on skin
x-rays
type of electromagnetic radiation
primarily used for medical imaging
gamma-rays
short wavelength
high frequency, high energy
photon released during radioactive decay
part of electromagnetic spectrum
electromagnetic waves
transverse waves bc the oscillating electric and magnetic field vectors are perpendicular to the direction of propagation
electric and magnetic fields are also perpendicular to each other
electromagnetic spectrum
describes the full range of frequencies and wavelengths of electromagnetic waves
(high energy to low energy) gamma rays–>x-rays–>UV–>visible light –>infrared–>microwaves–>radio waves
speed of light
all electromagnetic waves travel at the same speed
constant represented by c and is ~3.00e8 m/s
c=f(gamma)
c is speed of light, f is frequency, gamma is wavelength
visible spectrum
part of spectrum perceived as light by the human eye
between wavelengths of 400 nm (violet) and 700 nm (red)
light containing all colors at equal intensity is perceived as white
perceiving light
an object that appears red is one that absorbs all colors of light except red
absorbs all wavelengths except the wavelength of the color we see
this implies that a red object under green illumination will appear black, bc it absorbs the green light and has no light to reflect
blackbody
refers to an ideal absorber of all wavelengths of light
would appear completely black if it were at lower temp than its surroundings
rectilinear propagation
when light travels though a homogeneous medium it travels in a straight line
geometrical optics
explains reflection and refraction
and the applications of mirrors and lenses
describes the behavior of light at the boundary of a medium or interface b/w 2 media
reflection
rebounding of incident light waves at the boundary of a medium
light waves that are reflected are not absorbed into the second medium but bounce off the boundary and travel back though the first medium
law of reflection
theta1=theta2
the incident angle is the same as the reflected angle
both measured from normal
normal
a line drawn perpendicular to the boundary of a medium
all angles in optics are measured from the normal not the surface of the medium
mirror images
images created can be real or virtual
one of the distinguishing features of real images is the ability of the image to be projected onto a screen
real images
image is real if the light actually converges at the position of the image
image can be projected onto a screen
virtual images
image is virtual is the light only appears to be coming from the position of the image but does not actually converge there
plane mirrors
flat reflective surfaces
parallel incident light rays remain parallel after reflection
cause neither convergence nor divergence of reflected light rays
always create virtual images
create the appearance of light rays originating behind the mirrored surface
spherical mirrors
come in 2 varieties: concave and convex
the mirror can be considered a spherical cap or dome taken from a larger spherically shaped mirror
have a center of curvature (C) and a radius of curvature (r)
center of curvature (C)
is a point on the optical axis located at a distance equal to the radius of curvature from the vertex of the mirror
would be the center of the spherically shaped mirror if it were a complete sphere
concave mirror
look from the inside of a sphere to its surface
like looking into a cave
are converging mirrors
cause parallel incident light rays to converge after they reflect
convex mirror
look from the outside of a sphere
are diverging mirrors
cause parallel incident light rays to diverge after they reflect
focal length (f)
is the distance b/w the focal point (F) and the mirror
f=r/2
3 mirror distances
focal length (f)
o is the distance b/w the object and the mirror
i is the distance b/w the image and the mirror
relationship of the distances
1/f=1/o+1/i=2/r
all values must use the same units
image distance (i)
distance b/w the image and the mirror
1/i=1/f-1/o=2/r-1/o
if image is positive (i>0) then it is a real image
if image distance is negative (i<0) it is virtual and located behind the mirror
magnification (m)
is a dimensionless value that is the ratio of the image length to the object distance m=-i/o negative m signifies and inverted image postive m signifies an upright image m1 image is larger than object m=1 image is same size as object
ray diagram
useful for getting an approximation of where an image is
image types with a single lens or mirror
assuming o is postive
IR (infrared) and UV (ultraviolet) light
IR–> Inverted images are always Real
UV–> Upright images are always Virtual
sign of o
positive o: object is in front of mirror
negative o: extremely rare, object is behind mirror
sign of i
determines if real or virtual
postive i: real, image in front of mirror
negative i: virtual, image is behind mirror
sign of r
determines converging or diverging
positive r: mirror is concave, converging
negative r: mirror is convex, diverging
sign of f
determines converging or diverging
positive f: mirror is concave, converging
negative f: mirror is convex, diverging
sign of m
determines if its inverted or upright, and if its enlarged or reduced positive m: image is upright negative m: image is inverted m>1: image is enlarged m<1: image is reduced m=1: image is same size
refraction
bending of light as is passes from one medium to another and changes speed
speed of light through any medium is always less than its speed through a vacuum
Snell’s law
relates the incident angle, refracted angle, and indices of refraction for 2 media
for a given medium: n=c/v
c is speed of light in vacuum, v is speed of light in medium, and n is index of refraction
index of refraction
ratio of the speed of light in a vacuum to the speed of light in a given medium
=1 in a vacuum
for all other materials it will be greater than 1
light entering a medium
when light enters a medium with higher index of refraction it bends toward the normal
when it enters a medium with lower index of refraction it bends away from normal
total internal reflection
phenomenon in which all the light incident on a boundary is reflected back into the original material
results with any angle of incidents greater than the critical angle
if the angle is greater all light gets reflected back into original material
occurs as light moves from medium with higher refractive index to a medium of lower index
critical angle
theta c=inverse sin(n2/n1)
refracted light ray passes along the interface b/w the 2 media
if angle is above the critical all light will be reflected
lenses
devices that act to create an image by refracting light
usually have spherical surfaces
there are 2 surfaces that affect the light path
light is refracted twice as it passes from air to lens and from lens back to air
converging lenses
thicker in the center (bulge out slightly)
reading glasses
needed for people who are farsighted (see far objects clearly)
diverging lenses
thinner at the center thicker at the edges
standard glasses
needed for people who are nearsighted (see near objects clearly)
lensmaker’s equation
1/f=(n-1)(1/r1-1/r2)
n is index of refraction of lens material, r1 is radius of curvature for first lens and r2 is radius for second lens
sign of o for lenses
positive o: object is on same side of lens as light source
negative o: rare, object is on opposite side of lens from light source
sign of i for lenses
determines real or virtual
positive i: real, image is on opposite side of lens from light source
negative i: virtual, image is on same side of lens as light source
sign of r for lenses
determines converging or diverging
positive r: lens is convex, converging
negative r: lens is concave, diverging
*type of lens is opposite from mirror but converging and diverging is the same
sign of f for lenses
determines converging or diverging
positive f: lens is convex, converging
negative f: lens is concave, diverging
*type of lens is opposite from mirror but converging and diverging is the same
sign of m for lenses
determines upright or inverted
positive m: image is upright
negative m: image is inverted
lens power (P)
how optometrist describe a lens
P=1/f
P has the same sign as f
positive for converging lenses and negative for diverging lenses
bifocal lenses
corrective lenses that have 2 distinct regions
one that causes convergence of light to correct farsightedness, and second that causes divergence of light to correct nearsightedness
hyperopia
farsightedness
see far objects clearly
need converging lenses to correct
myopia
nearsightedness
see near objects clearly
need diverging lenses to correct
multiple lens systems
lenses in contact are a series of lenses with negligible distances b/w them
behave as a single lens w/ equivalent focal length
1/f=1/f1+1/f2+1/f3+…
P=P1+P2+P3+…
corrective contact lens
example of multiple lens system
worn directly on the eye
lenses not in contact
image of one lens becomes the object of another lens
image from the last lens is considered the image of the system
magnification of this type of system: m=m1Xm2Xm3X…
exp. microscopes and telescopes
spherical aberration
blurring of the periphery of an image as a result of inadequate reflection of parallel beams at the edge of a mirror or inadequate refraction of parallel beams at the edge of a lens
creates an area of multiple images w/ slightly different image distances at the edge of the image, appears blurry
dispersion
when various wavelengths of light separate from each other
common exp is the splitting of while light into its components colors using a prism
speed of light for different wavelengths
in a vacuum, all wavelengths have the same speed
in a medium, different wavelengths travel at different speeds
implies that the index of refraction of medium affects the wavelengths of light passing thought a medium bc index is related to speed of light
chromatic aberration
a dispersive effect within a spherical lens
leads to a rainbow halo at the edge of the image
depending on thickness and curvature of lens, may have significant splitting of white light, resulting in rainbow halo
corrected for in visual lenses with special coating
diffraction
spreading out of light as it passes though a narrow opening or around an obstacle
interference b/w diffracted light rays lead to characteristic fringes in slit-lens and double-slit systems
interference
interactions b/w waves traveling in the same space
may be constructive (waves adding together), destructive (waves canceling each other), partially constructive, or partially destructive
diffraction gratings
multiple slits arranged in patterns
can create colorful patterns similar to a prism as the different wavelengths interfere in characteristic patterns
x-ray diffraction
uses the being of light rays to create a model of molecules
often combined with protein crystallography during protein analysis
dark and light fringes do not take a linear appearance but a complex 2D image
plane-polarized light
light in which the electric field of all waves are oriented in the same direction
their electric field vectors are parallel, and so are their magnetic field vectors
the plane of the electric field dictates the plane of polarization
classification of stereoisomers
unpolarized light
random orientation of its electric field vectors
sunlight and light emitted from a light bulb
classification of stereoisomers
the optical activity of a compound due to the presence of chiral centers causes plane-polarized light to rotate clockwise or counterclockwise by a given number of degrees relative to its concentration (specific rotation)
polarizers
filters which allow only light with an electric field pointing in a particular direction to pass through
often used in cameras and sunglasses
if beam of light passes though a polarizer it will only let through that portion of light parallel to the axis of the polarizer
circular polarization
rarely seen natural phenomenon
results from the interaction of light with certain pigments or highly specialized filters
have uniform amplitude but a continuously changing direction
which causes a helical orientation of prorating wave
