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Optics IV


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bioluminescence
a plant or animal being able to produce light
incandescent
describes light produced by an object, such as a metal, that is at a very high temperature
flourescent
describes light emitted by some substances when they are exposed to electromagnetic radiation
phosphor
substance that glows after being exposed to energized particles
Chemiluminescence
(in chemical reactions) the emission of light by an atom or molecule that is in an excited state.
electroluminescence
process of transforming electrical energy directly into light energy
light-emitting diode (LED)
electroluminescent light source made from a semiconductor
ray model of light
model representing light as straight lines, called rays, that show the direction in which light travels
umbra
part of a shadow in which all light rays from the light source are blocked
penumbra
area of partial shadow from a non-point light source
regular reflection
..., Reflection that occurs when parallel rays of light hit a smooth surface and all reflect at the same angle
Diffuse reflection
if a surface is rough, the reflected light is sent out in a variety of directions
geometric optics
science of how light reflects and refracts
image
..., a copy of an object formed by reflected or refracted rays of light
optical device
technology that uses light
angle of reflection
ngle between the reflected ray and the normal
law of reflection
a scientific law stating that when light reflects off a surface, the angle of incidence always equals the angle of reflection; refers to the predictable behaviour of reflected light
vertex
middle point of a curved mirror
principal axis
an imaginary line, parallel to the tangent of a curved mirror that meets it at the vertex, on which the focal point, and generally the object, is placed
distance to object
the distance from the vertex to the object
distance to image
the distance from the vertex to the image
concave mirror
..., a mirror with a surface that curves inward
convex mirror
..., a mirror with a surface that curves outward
diverging mirror
reflecting surface that curves outward; also called a convex mirror
solar oven
cooking device that uses light from the Sun as its energy source; also called a solar cooker
magnification (M)
measure of how much larger or smaller an image is compared with the object itself
optical fibre
solid strand of glass that can transmit light, even around corners
medium
A substance through which signals can travel (e.g. air for sound waves).
interface
A line between the mediums that the light will be passing through, showing where they meet
speed of light (c)
3.0 * 10^8, in a vacuum
v
The index of refraction n is defined as , where c is the speed of light in air, and _______ is the speed of light in a material.
index of refraction (n) (also called refractive index)
amount by which a transparent material decreases the speed of light; indicated by a number, found by dividing the speed of light in a vacuum by the speed of light in that material
Snell's Law
ni sine theta = nr sine theta
mirage
An image of a distant object caused by refraction of light as it travels through air of varying temperature.
axis of symmetry
imaginary vertical line drawn through the optical centre of a lens
diverging lens
lens that is thinner at the centre than at the edges; also called a concave lens
concave lens
..., a lens that is thinner in the middle than at the edges
converging lens
lens that is thicker at the centre than at the edges; also called a convex lens
convex lens
..., a lens that is thicker in the middle than at the edges
thin lens equation
equation that states the relationship of the distance of an object from the lens (do), the distance of the image from the lens (di), and the focal length of the lens (f): 1/f = 1/di + 1/do
Luminous
Emits own light eg: light globe, sun
Non-luminous
Does not emit own light eg. moon, person
Incandescence
A process that makes light with heat
Sun
Example of a luminous object
Electric discharge
The process of producing light by passing an electric current through a gad
Lightning
An example of an electric discharge through a gas
Phosphorescence
Producing light by the absorption of ultraviolet light resulting in the emission of visible light over an extended period of time
Fluorescence
Immediate emission of visible light as a result of the absorption of ultraviolet light
Example of a phosphorescence
Glow in the dark stickers
Example of fluorescence
Whiter clothes after a detergent
Incandescent bulbs
Fluorescent lights are up to five time more energy efficient than _______
Light sticks
Example of chemiluminescence
Example of bioluminescence
Glow from a firefly
Triboluminescence
luminescence produced by friction, usually within a crystalline substance.
led
Light produced as a result of an electric current flowing in semiconductors
semiconductor
A material that allows a current to flow in only one direction
opague
Objects behind the material cannot be seen at all ; when a material does not transmit any incident light
light ray
A line on a diagram representing the direction and path that light is traveling
mirror
Any polished surface reflecting an image
shiny thin film on the back
The reflective part of a mirror is the _______
flat
Plane
Perpendicular
A wave in which the vibration of the medium is _______ to the direction in which the wave travels is called a transverse wave.
specular reflection
Reflection of light off a smooth surface
disco ball
Example of specular reflection
water surface with waves
Example of diffuse reflection
1.law of reflection
angle of incidence, angle of relfection
size attitude location type
What does SALT stand for?
lateral inversion
The orientation of an image in a plane mirror that is backwards and in reverse order
centre of curvature
The centre of the sphere whose surface has been used to make the mirror
converge
come together
inverted, real image
When an object is beyond C, at C, or between C and F, the reflected rays actually meet in front of the mirror, forming an _______ each time
diverge
spread out
different optical densities
What causes refraction?
Angle of Refraction
The amount the light bends
1.rule of refraction
incident ray, refracted ray, normal
toward
2.rule of refraction
away
2.rule of refraction continued
partial reflection and refraction
Light can be both reflected and refracted at the same time
3.00 x 108 m/s
Light travels at the speed of _______
n=c/v
The index of refraction n is defined as _______, where c is the speed of light in air, and v is the speed of light in a material.
n= sin i/sin r
What is the formula for the index of refraction in sine ?
critical angle
Sin theta= n2/n1
slowly
Total internal reflection occurs when :
Large
An object with a _______ heat capacity can absorb a lot of heat without undergoing much of a change in temperature.
retro-reflector
An optical device in which the emergent ray is parallel to the incident ray
apparent depth
The depth that an object appears to be at due to the refraction of light in a transparent medium
example of mirage
pool of water on a highway
emergent ray
The light ray that leaves a lens after refraction
do
Distance from the object to the optical centre
di
Prefix for 2
ho
height of the object
hi
Height of the image
f
1/T
Positive
Protons have a _______ charge
positive, virtual
Images distance(di) are _______ for real images and negative for _______images
positive, negative
The focal length (f) is _______ for converging lens and _______ for diverging lens
M= hi/ho = -di/do
What is the magnification equation?
focus
The point at which light rays parallel to the principal axis converge when they are reflected off a concave mirror