Light and Optics Flashcards
Myopia
nearsighted, far is blurry diverging lens (concave) because retina is too far back and object far away will form in front of the retina
Hyperopia
farsighted, near is blurry converging lens (convex) because retina is located too far forward and the image forms behind the retina
upright images
are always virtual
real images
are inverted
what happens when the object is at the focal length?
no image is formed
Diverging lenses and mirrors
at any object distance
are all Small, Upright, and Virtual (SUV)
concave lens
convex mirror
Concave lens/mirror; object at infinity
focal length = image
tiny, inverted, real
excitation
molecules can absorb the energy of a photon causing an electron to move from the ground state to a higher energy state
emission
molecules can release the energy of an absorbed photon and return to a lower state of energy
what happens when some energy is lost to heat and light during emission
the emitted photo will have less energy than the absorbed photon and therefore will have a longer wavelength
this is fluorescence
fluorescence
when the energy emitted is less than the energy absorbed due to loss of energy through heat
the molecule will end up having a longer wavelength (long = low energy)
speed of light
c = 3 x 10^8 m/s
c= wavelength x frequency
electromagnetic waves
transverse waves that propagate through vacuum plus other mediums (air, water)
color scheme
smallest waves –> longest waves
gamma, xray, UV, VIBGYOR, IR, microwave, radiowave
energy of EM waves
E = hf = hc/wavelength
What changes when moving through a new medium?
wavelength and speed of light changes
frequency stays the same
How to remember when something is virtual or real image?
When the image is produced in front of something you will need to push it forwards to get it to hit the retina (myopia –> diverging lens) = virtual
When the image is in back of something you will need to move it backwards to hit the retina (hyperopia –> converging lens) = real
Real people come back for their friends, virtual friends will move on
dispersion
the separation of light into colors
lower frequency (red) has a lower index of refraction
higher frequency (violet) has a higher index of refraction
chromatic aberration
formation of blurry objects due to the effects of dispersion through a lens
objects that are clear in one frequency (red) will become blurry if changes frequency to violet because violet has a larger dispersion than red does
spherical aberration
no unique focus point because there is more refraction than predicted
will affect all frequencies equally
Snell’s Law
n1sin(theta) = n2sin(theta)
How does light refract when the index of refraction is higher in the second medium?
Will turn towards the normal because will move slower
How does the light refract when the index of refraction is lower in the second medium?
the light will bend away from the medium because it can travel faster
What the equation for the index of refraction
c/v
speed of light in a vacuum/speed of light in a medium
c= 3 x 10^8 m/s
refraction
bending of light rays when light crosses at an angle from one medium to another with a different index of refraction
lens strength
the measure of a lens’s refractive power
the greater the lens strength, the more light will bend
this is inversely related to the focal length which is the distance of the object to the created image
thin lens equation
S = 1/o + 1/i OR 1/f = 1/o+ 1/i
S= strength of lens
F = focal length
o = object distance
i=image distance
S is measured in dipoters (D) which is equal to inverse meters
How is the thin lens equation used differently for converging vs diverging lenses?
converging lens has a positive f and i
diverging lens has a negative f and i
magnification
height (image)/height(object) = -distance (image)/distance(object)
Thin film interference
multicolored arrays generated by reflection events that occur within a system composed of 2 layers of semitransparent media
intensity of light depends on constructive and destructive interference among waveforms of polychromatic light
some light travels through medium one and then is reflected, some light hits medium one and is reflected
this is influenced by thickness - some wavelengths can’t pass through and cause interference if too thick
surface tension and other effects can also cause multicolored arrays
diffraction
bending of light around physical corners or very narrow gaps
think of the slit experiment and how light becomes semi circular
reflection
once light is past the critical angle (90 degrees) everything will be reflected back onto the same surface
