Light and Optics Flashcards
Radio waves are
Long, low frequency
Gamma rays are
Short, high frequency
Order of light lowest to highest
Radio,microwave,infrared, visible, UV, x-ray, gamma
Electromagnetic waves can travel through a vacuum because
Magnetic and electric fields causes reciprocal changes in each other independent of matter
A=angstrom
10^-10 m
Speed of light
c=3 x 10^8
Speed equation
c=f(wavelength)
Red light wavelength
400 nm
Violet light wavelength
700 nm
Blackbody
Ideal absorber of all wavelengths that would appear completely black at a lower temp than surroundings
Rectilinear propagation
When travels through a homogeneous medium, it travels in a straight line
Reflection
Rebounding of incident light waves at a boundary of a medium
Law of reflection
Angle 1=Angle 2
Normal
Line drawn perpendicular to the boundary of a medium
Real image
If light actually converges at the position of the image
Can be projected on a screen
Virtual image
If light only appears to be coming from the position of the image, but doesn’t converge there
Plane mirror
Flat and reflective, causes no convergence or divergence of reflected light ray
Plane mirrors always create
Virtual images, because the light doesn’t converge
Create the appearance of light rays originating from behind the mirrored surface
O
Object
I
Virtual reflected image
Center of curvature
C= point on the optical axis located at a distance equal to the radius of curvature from the vertex of the mirror
(If it were a complete sphere)
Concave surface
Inside sphere
Concave like looking into a cave
Convex
Looking on the outside of a sphere
Where is the center of curvature for a concave surface
In front of the mirror
Where is the center of curvature for a convex mirror?
Behind the mirror
Converging mirrors
Concave
Diverging mirrors
Convex
Lenses- converging lens
Convex
Lenses-diverging lens
Concave
focal length
f=distance between focal point (F) and the mirror
f for all spherical mirrors
f=r/2
o
distance between object and mirror
i
distance between image and mirror
Relationship of focal length and distances
1/f=1/o + 1/i=2/r
Image with positive distance (i)
Real image (in front of the mirror)
Image with negative distance (i)
Virtual distance (behind mirror)
Plane mirrors have what kind of focal length
infinitely large
Plane mirrors have what kind of radius and
Infinite
What is the image distance for plane mirrors
i= -o
Same distance in front as behind
Magnification
m= -i/o
Negative magnification
inverted image
Positive magnification
Upright image
If |m| is less than one
Image is smaller than object
If |m| is larger than one
Image is larger than object
If |m| =1
Image is the same size as the object
When the object is at the focal point
Reflected rays are parallel and the image is at infinityy
If object is outside the focal point of a concave mirror
The image is real, inverted, and magnified
If the object is inside focal point of a concave mirror
Image is behind mirror, enlarged, and virtual
For a concave mirror, a light ray that is reflected parallel to the mirror
The light is reflected back through the focal point
For a concave mirror, light that is reflected through the focal point
Is reflected parallel to the mirror
For a concave mirror, light that is reflected at the axis intersection of the mirror,
Is reflected back with the same angle from the normal
Image is
Where the reflected light converges
A convex mirror only forms
A virtual, upright, reduced image
Focal length for converging mirrors and lenses
Positive
Focal length for diverging mirrors and lenses
Always be negative
When would focal length and radius be negative
Convex, diverging lens
Converging lenses or mirror, Inverted images are always (IR)
real
Converging lenses or mirror, upright images are always (UV)
virtual
Refraction
Bending of light as it passes from one medium to another and changes speed
Index of refraction
n=c/v
n=index of refraction
Snell’s law
n1sin1=n2sin2
When light enters medium with a higher index of refraction
Bends towards normal
When light enters medium with a lower index of refraction
Bends away from normal
Critical angle (thetac)
Where refracted angle 2=90 degrees
Critical angle equation
Angle c=sin ^-1 (n2/n1
Total internal reflection
All light incident on a boundary is reflected back into the original material
With any angle greater than critical angle
When does total internal reflection occur?
When moving from a medium with a higher refractive index to a lower one
Lenses
Two surfaces that affect light path and 2 focal points
Converging lenses are
Thicker at the center
Diverging lenses are
Thinner at the centre
Parallel lines into a converging lens will
Converge
Parallel lines into a diverging lens will
Diverge
Lensmaker’s equation
1/f=(n-1)(1/r1-1/r2)
What lens has a negative focal length and radius?
Concave
What lens has a positive focal length and radius?
Convex
If a ray enters the center of a lens
It continues straight through with no diffraction
Ray parallel to axis on lens
Will refract trhough focal point on other side of lens
Ray through focal point before lens
Refracts parallel to the axis
Real side of a lens
Opposite of where it goes in, where the light goes after interaction
Virtual side of lens
Side same as light source
A convex lens is a
converging lens
A concave lens is a
Diverging lens
Power
P=1/f
in diopters
Nearsightedness
Myopia
Farsightedness
Hyperopia
Multiple lens focal lengths
1/f=1/f1 + 1/f2 + 1/f3…
Equivalent power of multiple lenses
P=P1 + P2 + P3
Multiplication of multiple lenses
m=m1 x m2 x m3
Spherical aberration
Blurring of the periphery of an image as result of inadequate reflection of parallel beads at the edge of a lens- multiple images with different image distances
Because index of refraction affects speed of light, it also affects
Wavelength
Dispersion
When various wavelengths of light separate from each other
What does not change as light enters a medium with different index of refraction
Frequency
What light experiences the least amount of refraction through a prism?
Red, smaller wavelength (slower)
Diffraction
Spreading out of light as it passes through a narrow opening or around and obstacle
As light moves through a very small slit it,
Diffracts, spreads out
Location of dark fringes equation
asin=n(wavelength)
a=width of slit
angle=dark fringe to lens center and axis
n=number of fringe
Interference
Displacement of waves added together
Where are bright fringes
Halfway between dark fringes
Equation for double slip dark fringe position
dsin=(n +1/2)(wavelength)
d=distance between 2 slits
Diffraction grating
Multiple slits arranged in patterns -creates many colors- interference of reflected rays
Plane polarized (linearly polarized) light
Light in which electric fields of all waves are oriented in the same direction - stereoisomers
