Optics Unit Test Flashcards
What’s a wave
A disturbance that transfers energy from one point to another without transferring matter
Crest
Highest point in a wave
Trough
Lowest point in a wave
Wavelength
the distance from one place in a wave to the next similar place on the wave
Amplitude
the wave height from the rest position of the wave to the crest or the wave depth from the rest position to the trough
Frequency
the rate of repetition of a wave
As frequency increases
the wavelength decreasss
As frequency decreases
the wavelength increases
Drawing a Wave
- Make a rest position depending on the amplitude
- Mark how long the wavelength is
- Mark the middle of the wavelength
- Mark the middle of that wavelength, creating half
- Mark the crest depending on the amplitude
- Mark the trough depending on the amplitude
- Draw the wavelength and label everything
Speed Over Wave is…
V = λ x f
the triangle!
V
f λ
v = f x λ f = v/λ λ = v/f
Light is an…
electromagnetic wave
Electromagnetic Radiation
Wave pattern made of electric and magnetic fields that can travel through empty space (sound isn’t electromagnetic!)
Electromagnetic Spectrum
Range of electromagnetic radiation arranged from shortest (gamma rays) to longest (radio waves)
- The wavelength (and therefore the frequency) of a light wave will depend on the scale of the disturbance in the EM fields
Order of the Electromagnetic Spectrum
- Radio Waves
- Microwaves
- Infrared Waves
- Visible Light
- Ultraviolet rays
- X-rays
- Gamma Rays
Radio waves
The longest wavelength and lowest frequency waves. Used to transmit television signals and important for many forms of communication
Microwaves
Shorter wavelengths than radio waves. Used in cell phones, radio, and cooking food.
Infrared waves
Have shorter wavelengths than microwaves but longer wavelengths than visible light. Used to detect the formation of new stars in nebulas due to the heat they give off.
Visible light
The part of the spectrum that human eyes can visibly detect. Red light has the longest λ, ~700 nm. Violet light has the shortest λ, ~400 nm.
Ultraviolet rays
Have shorter wavelengths than visible light. Can be used to create sterile environments and treat jaundice in babies, too much can cause sunburn
X-rays
Very high energy radiation, penetrate human tissue. Used in medical practices to see internal structures, used to study black holes
Gamma rays
Extremely high energy radiation, penetrate human tissue. Used to target and kill cancer cells, study black holes.
White light is composed of…
Different colour wavelengths of visible light
Primary colours
red, blue, green (RBG)
Blue + Red = Magenta
Blue + Green = Cyan
Red + Green = Yellow
Secondary Colours
magenta, cyan, yellow
Mix two equal amounts of primary to make secondary
When mixed correct amount of all the primary colours you will make…
white light
Blue + Green + Red = White
When mixing a primary with a secondary you will make…
white
Green + Magenta = White
Blue + Yellow = White
Red + Cyan = White
Primary Colours (subtractive)
Magenta, Yellow, Cyan
When a lightwave strikes an object, some wavelengths of light will…
reflect
The colour you see when you look at an object depends on the…
Wavelengths that are reflected
Coloured matter selectively…different colours or wavelengths of light and the colours that are absorbed are…from the reflected like that is seen
- absorbs
- retracted
Primary and secondary colours of light for the subtracted theory are…to the colours of the additive theory
- opposite
Magenta + Cyan = Blue
Cyan + Yellow = Green
Yellow + Magenta = Red
When all three subtractive primary colours are mixed they make…
black
When a colour is absorbed…
You will only see…
- it will not make it to your eye
- reflected colours
Primary Reflected/Absorbed
In blue objects: blue reflected, red green absorbed
In red objects: red reflected, green red absorbed
In green objected: green reflected, blue red absorbed
Secondary Reflected/Absorbed
In cyan objects; green + blue reflected, red absorbed
In magenta objects: blue + red reflected, green absorbed
In yellow objects: green + red reflected, blue absorbed
Called the subtracted colour theory because…
colours that are absorbed are “subtracted,” not seen
Luminescence
light generated without heating the object
Phosphorescent
light emitted without heat and is slower than fluorescence
Triboluminescence
light generated when substances are ripped, crushes, or rubbed together
Chemiluminescence
production of light from a chemical reaction
Incandescent
light emitted by hot objects
Electro Luminescence
crystals, flowing electrons, no heat
Ray Model of Light
If light travels freely through =transparent
If light is not transmitted by an object= opaque.
If some light transmits through =translucent.
Incident ray
original incoming ray
Reflected ray
ray that bounces off a mirror
Normal
a line that is perpendicular (right angle to) the reflecting surface.
Angle of incidence
angle between the incident ray and the normal.
Angle of reflection
angle between the reflected ray and the normal.
Plane
flat
Transmitted
— pass through the object
Refracted
— light bends as it is absorbed by the object
Reflected
— light is scattered from the object
Law of Reflection
The law of reflection states that when an object hits a surface, its angle of incidence will equal the angle of reflection.
Plane Mirrors Instructions
- Label your incident ray
- Label your reflected ray
- Measure 90 degrees from the incident ray and make a mark
- Draw a “normal” & label it (dotted)
- Count from the 90 on the given angle
- Count from the 90 on the other side, make a mark, draw a line
- Label your degrees of incidence and of reflection
Plane Mirrors Characteristics
L (Location) - behind mirror
O (Orientation) - upright
S (Size) - Same
T (Type) - Virtual
Converging Concave Mirror Instructions
- Ray goes through the top of the object, parallel to PA and reflects through F (focal point).
- Ray goes across the top of the object, through F and reflects parallel to the PA.
- You can check for accuracy with a ray from the top of the object through C (center of C).
Concave Object Beyond C
Image L - Between C+F O - inverted S - smaller T - real
Concave Object Between C and F
Image L - Beyond C O - inverted S - larger T - real
Concave Object at F
GO THRU C
Parallel
NO IMAGE
Concave Object Between ‘F’ and ‘V’
***LAW OF REFLECT ALWAYS** L - Behind mirror O - upright S - larger T - virtual
Concave Object At C
L - At ‘C’
O - inverted
S - same
T - real
Diverging Convex Mirror Instructions
- Try and go from the top through f, hit the mirror, draw dotted line behind mirror
- Try and go thru c, hit mirror, dotted line
Diverging Convex Characteristics
L - behind mirror
O - Upright
S - Smaller
T - Virtual
Magnification Triangles
hi
m ho
di
m do
what’s the order for mirrors
concave
c, f, mirror
convex
mirror, c, f
whats the order for lenses?
2F’ F’ O F 2F
Instructions for Convex (Converging Lenses are Fat)
- First ray goes from the top of the object and refracts through lens to F
- Second ray goes from the top of the object though O (optical center)
- Where the rays meet is the top of the image
- When object is closer to the lens than F, first ray is extended back in front of object to meet second ray (Between lens and F’)
Convex Lens Beyond 2F’
L - Between F & 2F
O - inverted
S - smaller
T -real
Convex Lens At 2F’
L - At 2F
O - inverted
S - same size
T - real
Convex Lens Between F’ and 2F’
L - Beyond F
O - inverted
S - larger
T - real
Convex Lens At F’
No image
paralell
Convex Lens Between lens and F’
Beyond 2F’ upright bigger virtual *extend the rays*
Instructions for Concave (Diverging Lenses are Skinny)
- First ray goes from top of the object parallel to PA and refracts up when it goes through lens
- Extend the ray back through F (at front of lens) with dotted (virtual) line
- Second ray travels from top of object through O (optical center) and does not bend
- Where rays intersect is top of the image
Concave Diverging Lenses Characterisics
L - between F & O
O - upright
S - smaller
T - virtual
Refraction
Refraction is the bending of light as it travels at an angle, from a material with one refractive index to a material with a different refractive index.
Rules of Refraction
- The incident ray, the refracted ray, and the normal all lie on the same plane. The incident ray and the refracted ray are on opposite sides of the line that separates the two media interfaces.
- Light bends towards the normal when the speed of light in the second medium is slower than the speed of light in the first medium.
- Light bends away from the normal when the speed of light in the second medium is faster than the speed of light in the first medium.
Fast -> Slow = Towards the normal (FST)
Slow -> Fast AWAY (SFA)
Index of refraction
The Index of refraction for a medium is defined as the ratio of the speed of light in a vacuum to the speed of light in that medium.
Index of refraction formula
n = c/v c = speed of light in a vacuum - 3.00 x 10^8 m/s v = speed of light in the material n = index of refraction of a material
The ? the index of refraction the ? the speed of light in the medium.
bigger
slower
Snells Law Formula
n1sin01 = n2sin02
LEDs
semiconductors that emit light and very little heat
bioluminescence
light emitted from living beings
nuclear fusion
Two or more nuclei combine and energy in the form of photons is released
Combustion
chemical process that release heat and light
Electromagnetic radiation
from a “hot body: very wasteful
Fluorescence
the emission of light by a substance that has absorbed light
electric discharge
release and transmissions of electricity in an applied electric field through a medium such as a gas
