Lect. 8 Light & Optics

Question 1

transverse wave
travelling oscillation of an electric and magnetic field (perpendicular to each other)
direction of propogation is perpendicular to both fields

Answer 1

electromagnetic wave

Question 2

constant value for each particular wave

= E / B

Answer 2

speed of an electromagnetic wave (c) through a vacuum

Question 3

a small sliver from the electromagnetic spectrum

includes wavelengths 390 - 700 (*10^-9 nm)

Answer 3

light

Question 4

“color” / wave in electromagnetic spectrum w/ the highest energy, shortest wavelength, and highest frequency
travels slowest through a medium (700)

Answer 4

violet light

Question 5

“color” / wave in electromagnetic spectrum w/ the lowest energy, longest wavelength, lowest frequency, travels fastst through a medium (390 nm)

Answer 5

red light

Question 6

“beyond violet”

just beyond the visible spectrum on the smaller wavelength side; very high in energy

Answer 6

Ultraviolet Light

Question 7

just beyond visible spectrum on the longer wavelength side; very low in energy

Answer 7

Infrared light

Question 8

Equation: speed of light (wavelength w/ corresponding frequency)

Answer 8

c = f * wavelength

Question 9

used to find the speed of light constant through some medium

compares c in a vacuum to c through some medium

Answer 9

Index of Refraction (n)

Question 10

Equation: index of refraction (n)

Answer 10

n = c / v

Question 11

All media have an index of refraction (n) ____ than 1.

Answer 11

greater than

Question 12

A higher index of refraction (n) indicates that a wave moves _______ through the medium

Answer 12

slowly

Question 13

Index of refraction for water

Answer 13

n (water) = 1.3

Question 14

Index of refraction for glass

Answer 14

n (glass) = 1.5

Question 15

light w/ electric fields all oriented in the same direction

Answer 15

plane-polarized light

Question 16

The dual nature of light states that light acts like a ____ and a _____.

Answer 16

wave and a particle

Question 17

angle at which a light ray strikes an interface

Answer 17

angle of incidence

Question 18

angle at which light ray is reflected off an interface

Answer 18

angle of reflection

Question 19

angle at which a light ray may refract off an interface

ange of incidence = angle of reflection

Answer 19

angle of refraction

Question 20

Equation: Snell’s Law

-Described angle of Refraction

Answer 20

n1 * sin(ø)1 = n2 * sin(ø)2

Note: n1 and n2 = respective interfacing media; doesn’t matter which is which

Question 21

When light crosses into a new medium, _____ is constant but ____ changes.

Answer 21

frequency is constant but wavelength changes

Question 22

If the index of refraction (n) goes up, light slows down and ______ shortens

Answer 22

wavelength

Question 23

If the index of refraction (n) goes down, light ______ and wavelength lengthens

Answer 23

speeds up

Question 24

Equation: Energy of a Photon

Answer 24

E = h * f

Note: h = Planck’s constant

Question 25

If the frequency is doubled in the energy for a single photon, you also double the number of photons and increase intensity by _____

Answer 25

4

Question 26

if the angle of incidence is large enough, all photons reflect and none refract;

Answer 26

total internal reflection | Note: angle is called the CRITICAL ANGLE

Question 27

white light is split into FREQUENCIES of the visible spectrum by a prism

Answer 27

chromatic dispersion

Question 28

bending waves around a corner through a small opening

Answer 28

diffraction

Question 29

when diffracting light, a smaller hole _____ spreading of the light

Answer 29

increases

Question 30

diffraction can create light/dark bands or colors by ____ when waves meet

Answer 30

interference

Question 31

interference that results in bright bands

Answer 31

constructive interference

Question 32

interference that results in dark bands

Answer 32

destructive interference

Question 33

Mirrors _____ light

Answer 33

reflect

Question 34

lenses _____ light

Answer 34

refract

Question 35

an image that does not actually exist except to the observer; no light rays come from this image; Ex: reflection in a flat mirror; mirage, fish seen from shore

Answer 35

virtual image

Question 36

an image that exists separately from the observer; rays of light intersect and emanate from the point of intersection

Answer 36

real image

Question 37

mirror that is curved out to the observer

Answer 37

convex mirror

Question 38

mirror that is curved in, away from the observer

Answer 38

concave mirror

Question 39

lens that acts like a concave mirror

Answer 39

converging lens

Question 40

lens that acts like a convex mirror

Answer 40

diverging lens

Question 41

if the center of a lens is thicker than its ends, it will _____ light regardless of the shape or which direction light moves through the lens

Answer 41

converge | thiCker Center Converges

Question 42

If the center of a lens is thinner than its ends, it will _____ light

Answer 42

diverge

Question 43

small section of a curve that could be extended to form a perfect circle; radius of a small section is = to the radius of the entire circle smaller value means a sharper curve

Answer 43

radius of curvature

Question 44

type of mirror (ex: convex / concave) only parabolically curved surfaces will focus all parallel lines to a single focal point; all equations require rays of light at small angles

Answer 44

spherical mirrors

Question 45

light from horizontal rays is reflected by concave mirrors or refracted by converging lenses to focus on a single point Affected by: refractive index of lens, medium lens is in, and radius of curvature

Answer 45

focal point

Question 46

Convex mirrors and diverging lenses reflect/refract horizontal rays ________, found by tracing back along the reflected or refracted ray behind the mirror/lens

Answer 46

outward from a single point

Question 47

focal point for any mirror or lens is separated from the mirror or lens by the ____

Answer 47

focal length

Question 48

Equation: focal length of mirror related to radium of curvature

Answer 48

f(mirror) = 1/2 * r

Question 49

quality of a lens that is inverse of focal length measured in diopters SI unit = 1 / m

Answer 49

Power

Question 50

ratio of the size of the image to the size of the object can compare height of the image to the heigh of the object = negative ratio of distance of the image over the distance of the object from the light source

Answer 50

lateral magnification (m)

Question 51

Equation: Lateral Magnification

Answer 51

m = - d(i) / d(o) = h(i) / h(o)

Question 52

the closest distance an object can be to an individual while they can still focus clearly on the object

Answer 52

near point

Question 53

angle occupied by an object when at the near point compared to the angle occupied by the image of the object when in front of a lens

Answer 53

angular magnification: m(q)

Question 54

Equation: Angular magnification

Answer 54

m(ø) = ø(image) / ø(np)

Question 55

Equation: Thin Lens Equation

Answer 55

1/f = 1 / d(o) + 1 / d(i) Note: f = focal length Applicable to any mirror or lens

Question 56

Mirror that makes a positive, real, inverted image | unless object is w/i the focal distance!

Answer 56

concave mirror

Question 57

mirror that always makes a negative, virtual, upright image

Answer 57

convex mirror

Question 58

type of lens that makes a positive, real, inverted image | unless object is w/i the focal distance!

Answer 58

converging lens

Question 59

type of lens that always makes a negative, virtual, upright image

Answer 59

diverging lens

Question 60

for a _____ mirror and a _____ lens, focal length is always negative

Answer 60

convex mirror | diverging lens

Question 61

for a ______ mirror and a ____ lens, focal length is always positive

Answer 61

concave mirror | converging lens