em waves and optics test 4/15/24

when a ray of light changes mediums

speed and wavelength change but frequency stays the same

a proton that is being accelerated

produces electromagnetic radiation

charged objects

generate electric fields

when charged objects move

electric fields change and produce magnetic fields

changing magnetic fields produce

electric fields

in electromagnetic waves

the electric and magnetic fields are perpendicular

electromagnetic waves do not require

a medium

EM waves are generated by

waving a charge back and forth

as the index of refraction increases

the medium becomes slower

n =

c (speed of light in a vacuum) / v (speed of light in medium

wein’s law

the electromagnetic radiation produced by an object depends on its temperature

specular reflection

parallel light rays are reflected parallelly

diffuse reflection

parallel light rays are scattered by irregularities in the surface

plane mirror

image is upright, same size, same distance from mirror, and virtual

law of reflection

thetai = thetar, angles measured to the normal

refraction

bending of light while passing through a material with a different IOR than the original one; some light still reflected off the surface

snell’s law/law of refraction

n1sintheta1 = n2sintheta2 , indices and angles of incidence and refraction respectively, measured to the normal

graph of V = c/n

decreasing exponential (think ^-1)

wavelengths change with corresponding differences in speed. equation?

n1/n2 = v1/v2 = lamda1/lambda2

power of lens equation

P = 1/f, where f is focal length. result unit is in diopters (D)

converging lens, object beyond 2F

inverted, real, smaller, between F and 2F

converging lens, object between F and 2F

inverted, real, larger, beyond 2F

converging lens, object between F and lens (magnifying glass)

upright, virtual, larger, between F and 2F on object’s side

diverging lens all cases

upright, virtual, smaller, between F and lens on object’s side

thin-lens equation

1/f = 1/do + 1/di, where f = focal length, do = object distance, di = image distance

in a divergent lens, the _ and _ are negative

focal length and image distance

magnification equation

m = hi/ho = -di/do , where hi and ho are the image and object heights

principal axis

imaginary line through center of curvature and center of mirror

focal point

where parallel rays converge after striking a mirror

mirror focal length equation

f = +- ½ R, negative for convex, R is radius of curvature

spherical aberration

rays far from the principal axis cross between F and mirror, fixed with a parabolic mirror

concave mirror, object beyond C

real, inverted, smaller, between C and F

concave mirror, object between C and F

real, inverted, larger, beyond C

concave mirror, object between F and mirror

virtual, upright, larger, behind mirror

convex mirror, all cases

virtual, upright, smaller, behind mirror between F and mirror

for convex mirror, focal length is

negative

critical angle

angle of incidence where refracted angle is 90

critical angle equation

thetac = sin^-1 n2/n1, where n1 > n2

total internal reflection

occurs at the critical angle, used for fiber optics, telescopes, reflectors, and cutting gemstones

dispersion

creates rainbows because each wavelength of light has a different IOR, splitting the colors as they bend through water droplets

in a mirror, any upright image is

virtual

in a mirror, any inverted image is

real