Optics Flashcards
What is light from incandescence?
The process of producing light as a result of high temperatures. He did objects begin to glow and eventually emit light
How do incandescent lightbulbs work?
Theremins wire made of tungsten, glows as electricity passes through it and becomes so hot it gives the visible light light. Only 5 to 10% of electricity is converted to like energy, the rest is converted to infrared light which can be felt as heat Which means that this is a very inefficient method of producing light. Thomas Addison was the inventor
How do you get light from electric discharge?
Flight from electric discharge is light that is produced by an electric current passing through a gas. electricity causes gas to glow. The electric energy excites the atoms, causing them to jump into a higher orbit (or energy level). When they jump down they give off energy as electromagnet radiation.
Neon, argon, helium, and krypton produce what light?
Ne: Red
Ar: violet/blue
He: gold
Kr: off white
How does light by phosphorescence work?
Materials are coated with phosphorus which absorbs light energy, especially UV light. The materials keep some of the energy and release some as visible light of lower energy. The rates of energy loss depends on the material and may take seconds today. For this reason they’re often called “glow-in-the-dark” materials
How does light from phosphorescence work?
An object absorbs UV light and immediately releases the energy as visible light.
What are some examples of fluorescence?
Laundry detergent have added fluorescent dyes. Therefore shirts tend to glow slightly which is apparent in even visible light since it contains a small amount of UV light. Highlighter pens, fluorescent lights
How do fluorescent lights work?
Uses both electrical discharge inflorescence. Light tube is filled with very low-pressure mercury vapor and the inner surface of the tube is coated with a fluorescent material. The electricity causes the Mercury atoms to emit UV light which strikes the fluorescent inner surface, resulting in the production of visible light.
What are the advantages of fluorescent lights?
They are 4 to 5 times more efficient than incandescent lightbulbs. They produce less heat, use less electricity and the bulbs last longer.
What are the disadvantages of fluorescent lights?
They are more expensive and contain mercury, which is toxic, so they cannot be disposed of with household waste, they must be taken to an appropriate recycling center.
How does the light from chemiluminescence work?
Chemiluminescence is the production of light as a direct byproduct of a chemical reaction. In this method almost no heat is produced.
How do glow sticks work?
Utilizes chemiluminescence. Two chemicals are originally separate in the glow stick, one is in a narrow small glass file in the middle of the glow stick and one is in the main body of the stick. Bending the stick breaks the small glass vial mixing the two chemicals. The chemical reaction produces light.
What are the advantages of glow sticks?
They are inexpensive to make, no electricity required, durable.
What is light from bioluminescence?
Chemiluminescence in living organisms. Enzyme Luciferase is needed for the reaction to occur.
Why do animals use bioluminescence?
Used for protection from predators, two lure pray and to attract mates
What is light from triboluminescence?
Triboluminescence is the production of light when certain crystals are scratched, crushed for rubbed
What is lights from a light emitting diode?
An electronic device that allows current to flow in only one direction. This is achieved by using special semiconductors like silicone.
How are LEDs different from incandescent bulbs?
They do not need filament, do not produce as much heat, and are more energy-efficient.
What is geometric optics?
The use of light rays to determine the path of light when it strikes an object
What is incident light?
The light emitted from an object
Define a transparent object
Lets light pass through it and objects behind it to be seen clearly
What is a translucent object?
Allows some light to pass through it but does not clearly show objects behind it
Define an opaque object
Does not allow any light pass through it. All incident light is absorbed or reflected and Objects behind it cannot be seen
Define image
The reproduction of an original object that is produced through the use of light
Define a mirror
Any polished surface that exhibits reflection. Common mirrors are made up of a front part, a sheet of glass. The back part is a thin layer of reflective silver or aluminum.
Define plane mirror
Flat mirror
What is the normal?
The line that is perpendicular or at right angles to the reflecting mirror surface. This is Drawn at the point where the incident ray strikes the surface of the mirror.
What is the angle of incidence?
The angle between the incident ray and the normal
What are the two laws of reflection?
- The angle of incidence equals the angle of reflection
2. The incident ray, the reflected ray, and the normal all lie in the same plane
What is true of a specular reflection?
A series of parallel rays strikes a flat reflective surface. The angles of incidence are identical, the angles of reflection are identical.
What is true of diffuse reflection?
If a series of parallel rays strike an irregular surface the ankles of incidence are different. The angles of reflection are different and would be scattered in different directions
Light rays and the laws of reflection help us determine what?
How and where an image is formed in a plane mirror
The sun produces what and why?
A tremendous amount of different types of energy through Nuclear reactions
How fast can like travel?
Around the earth 7.5 times in one second
How does light travel and what evidence is there of this?
In straight lines as evidenced by the formation of Earth’s shadow on the moon during a lunar eclipse as well as the sharp shadows produced by objects in the path of sunlight.
What is light?
An electromagnetic wave which is a form of radiation that does not require a medium for it to move through.
What is a medium?
Any physical substances that acts as a carrier for the transmission of energy.
What is conduction?
Heat energy transfer usually in solids
What is convection?
Heat energy transfer usually through liquids or gasses
Theory of light- 1801
Thomas Young. Light shows wave like properties
Theory of light, 1864
James Clerk Maxwell- Electricity and magnetism couple together to form a chain traveling through space, an electromagnetic wave, which requires no medium and travels at the speed of light
Theory of light – 1887
Heinrich Hertz discovered the existence of radiowaves which are a form of low energy electromagnetic wave.
Theory of light – 1895
William Konrad Roentgen discovered high energy electromagnetic waves which we now call x-rays
Draw a diagram of the electromagnetic spectrum
See text
What are the colors of visible light?
Red, orange, yellow, green, blue, indigo, violet. WhiteLight is a combination of all these colors
What might affect the speed of light?
All colors travel at the same speed in a vacuum. In different media each color travels slower than light in a vacuum.
How does red and violets differ?
Red has the least energies, the longest waves, and is slowed the least. Violet has the most energy, the shortest waves, and is slowed the most.
What is a luminous source?
Produces its own light
What is a nonluminous source?
Does not produce its own light but can only be seen by reflected light.
Image formed by mirrors appear to be located where?
Where all the reflected rays appear to meet.
What is a virtual image?
An image in which light does not arrive at or from e image itself. The light only appears to come from the image location. (The light rays converge behind the mirror)
What is a real image?
When the light is actually arriving at the image location. The image must be projected on a screen. The light rays converge in front of the mirror.
What is true about images in plane mirrors?
The plane mirror divides the object-image line in half and is perpendicular to that image
What is the SALT for images in plane mirrors?
S- Same as object
A- Upright but laterally inverted
L- Behind the mirror the same distance from the object
T- Virtual
What is a concave mirror?
Bulge inward in the middle. If parallel light rays are shown on its surface the reflected rays will converge
What is a convex mirror?
Bulge outward
Parallel light rays diverge
What is the center of curvature?
Center of sphere used to make mirror
What is the principle axis?
Line through the centre of curvature to midpoint of mirror
What is the vertex?
Where the principle axis meets the mirror
What is the focal point?
Point at which light rays parallel to the principle axis converge
What are three unique properties of lasers?
One. Lazers produce electromagnetic radiation of only one energy level.
Two. Waves travel in same direction
- Waves travel in unison.
Sketch a concave mirror with the object beyond C. Write the salt.
G
Draw a concave mirror with the object at C. Right the SALT
J
Draw a concave mirror with the object between C and F. Write the SALT
D
Draw a concave mirror with the object at F. Write the SALT
J
Draw an object in a convex mirror. Do the SALT.
See diagram.
