Physics Chapter 9: Light and Optics Flashcards
Mechanical waves travel fastest in
Solids (because of dense particle arrangement)
Electromagnetic waves (light) travels fastest in
A vacuum (because there’s no medium to interact with)
Single slit diffraction. A and theta are inversely proportional. If the aperture width A decreases (becomes smaller), the angle θ for the minima increases (the diffraction pattern spreads out)
Double slit diffraction maxima
Double slit diffraction minima
For humans, the clearest vision results when i
Is equal to the distance between the lens and the fovea. So i of 20mm will result in clear vision (distance between the lens and the fovea)
If an object is placed on the focal point what happens?
No image is formed
Refractive index equation and how does this affect the speed of different colors?
n = c/v
This formula gives the refractive index by comparing the velocity of light through a substance with the velocity of light. Blue light refracts the most and therefore would have a higher n
Red light refracts the least and therefore has the lowest n
If c is constant
This means red light travels faster than blue light
Converging (concave) mirrors produce
A real image that is inverted (upside down) if the object is outside the focal point.
A virtual image that is upright if the object is inside the focal point.
Diverging mirror (convex) produces
A virtual image that is always upright and reduced in size, regardless of the object’s distance.
Converging lens (convex lens) produces
A real image that is inverted if the object is outside the focal point.
A virtual image that is upright if the object is inside the focal point.
Diverging lens (concave lens) produces what kind of image
A virtual image that is always upright and reduced in size, regardless of the object’s distance.
Real images formed by, location, orientation, sign of i and type of MIRROR
Virtual images formed by, location, orientation, sign of i and type of MIRROR
Thin lens equation
Magnification equation
Tracing ray diagrams
1) draw one ray parallel to the normal as it approaches the mirror (from top of object)
2) draw one ray from top of object to the “ground”
How do real/virtual images differ for mirrors vs lenses
Real images for mirrors = in front of mirror
Real images for lenses = behind lens
real images are where the light actually goes
Visible light range
400 - 750nm
Red light wavelength
~750nm
violet light wavelength
~400nm
electric and magnetic components are both perpendicular to propagtion direction and to each other
EM waves
Can EM waves be polarized?
YES
direction of electric and magnetic fields rotates steadily over time. Can be either righhanded (clockwise) or lefthanded (ccw)
Circular polarization
Energy of a wave
E =hf = hc/ λ
Snell’s law
use for refraction
Total internal reflections happens when
the angle of the refracted ray reaches 90. Only occurs when moving into a medium with a smaller index of refraction (or when light is speeding up as it moves into a the new medium)
critical angle
When light isnt refracted, it’s reflected internally
Diffraction
when waves move through a barrier with a small opening they spread out
Pattern for single slit diffraction
one massive intensity peak
double slit diffraction
more evenly spaced minima and maxima
Power of a lens in diopters
P = 1/f, where f = focal point
Nearsighted is also called and corrected by what kind of lens
Can’t see far, also called myopia, lense refracts light too much, forming image in front of the retina.
corrected by diverging lens
farsighted is also called and corrected by what kind of lens
hyperopia, lens doesn’t bend light enough and forms image behind retina. can see far but not near
use converging lens
when is i positive for mirrors AND lens?
for REAL IMAGES (both mirrors and lens)
when is i negative for mirrors and lens?
for VIRTUAL (both mirrors and lens)
Focal length is +/- for Concave Mirrors?
+
Focal length is +/- for convex mirrors?
-
Focal length is +/- for concave lenses?
-
Focal length is +/- for convex lenses?
+
Definition of focal point
f = r/2. (-) for diverging lens and (+) converging lens
Difference between UV and ultrasound
UV = EMR, ultrasound is mechanical waves
A) because absorbed NEEDS to be less than the radiated to follow conservation of energy
