Light and optics Flashcards
Electromagnetic waves
transverse waves that consist of an oscillating electric field and an oscillating magnetic field. The two fields are perpendicular to each other and to the direction of propagation of the wave.
Electromagnetic spectrum
the range of frequencies and wavelengths found in EM waves. Em spectrum includes, rom lowest to highest energy, radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays
The visible spectrum
400 nm (violet) to 700 nm (red)
Reflection
is the rebounding of incident light waves at the boundary of a medium.
Law of reflection
states that the incident angle will equal the angle of reflection, as measure form the normal.
Spherical mirrors
have centers and radii of curvature as well as focal points.
concave mirrors
are converging systems and can produce real, inverted images or virtual, upright images, depending on the placement of the object relative to the focal point
convex mirrors
are diverging systems and will only produce virtual, upright images
Plane mirrors
produce virtual, upright images; these images are always the same size as the object. they may be thought of as spherical mirrors with infinite radii of curvature.
Refraction
is the bending of light as it passes form one medium to another. The speed of light changes depending on the index of refraction of the medium. This speed change causes refraction. The amount of refraction depends on the wavelength of the light involved; this behavior causes dispersion of light through a prism.
Snell’s law (law of refraction)
states that there is an inverse relationship between the index of refraction and the sine of angle of refraction (measured from the normal)
n1 = sin θ 1 = n2 sin θ 2
total internal reflection
occurs when light cannot be refracted out of a medium and is instead reflected back inside the medium. Occurs when light moves from a medium with a higher index of refraction to a medium with a lower index of refraction with a high incident angle.
critical angle
The minimum incident angle at which total internal reflection occurs
θ c = sin^-1 (n2/n1)
Lenses
refract light to form images of objects. Thin symmetrical lenses have focal points on each side. Convex lenses are converging systems and can produce real, inverted images or virtual upright images. Concave lenses are diverging systems and will only produce virtual, upright images. Lenses with non-negligible thickness use the lens maker’s equation.
Diffraction
bending and spreading out of light waves as they pass through a narrow slit. It may produce a large central light fringe surrounded by alternating light and dark fringes with the addition of a lens. Interference supports the wave theory of light.
Young’s double slit experiment
shows the constructive and destructive interference of waves that occur as light passes through parallel slits, resulting in minima 9dark fringes) and maxima (bright fringes) of intensity.
In lane-polarized light
all of the light rays have electric fields with parallel orientation. Plane-polarized light is created by passing unpolarized light through a polarizer.
Circularly polarized light
all of the light rays have electric fields with equal intensity but constantly rotating direction. Circularly polarized light is created by exposing unpolarized light to special pigments or filter.s .
speed of light
c = fλ
law of reflection
θ 1=θ 2
optics equation
1/f = 1/o + 1/i = 2/r
magnification
m=-i/o
Index of refraction
n = c/v
Lenmaker’s equation
1/f = (n - 1 )(1/r1 - 1/r2)
Power
P = 1/f . measure by diopters
Focal length of multiple lens system
1/f = 1/f1 + 1/f2 + 1/f3 + 1/fn
power of multiple lens system
P = P1 + P2 + P3 + Pn
magnification of multiple lens system
m = m1 x m2 x m3
positions of dark fringes in slit-lens setup
a sin θ = nλ
Positions of dark fringes in double slit setup
d = sin θ = (n + 1/2)λ
order of colors in spectrum from decreasing wavelength
ROY G BV .
Black body
refers to the ideal absorber of all wavelengths of light
Rectilinear propagation
when light travels through a homogenous medium, it travels in a straight line
if i>0, the image is
a real image
if i <0 not real
a negative magnification signifies
an inverted image. positive is upright.
if an ImI < 1
the image is smaller than the object (reduced) and vice versa.
convex mirrors are __ mirrors. Convex mirrors are __ mirrors
converging, diverging. vice versa for lens.
When light enters a media with higher index
it bends towards the normal. When enters with lower index bends away from normal.
hyperopia
far sightedness, needs lens that causes convergence of light
myopia
near sightedness, needs lens that causes divergence of light
Spherical abberation
blurring of the periphery of an image as a result of inadequate reflection of parallel beams at the edge of a mirror or inadequate refraction of parallel beams at the edge of a lens.
chromatic aberration
light dispersion within the glass lens heads to the formation of a rainbow halo at the edge of the image
light fringes and dark fringes
light fringes are the maxima between to light waves. Dark fringes (minima) are the destructive interference.
