OPTICS AND THE THEORY OF LIGHT Flashcards
REFRACTION AND REFLECTION
One billionth of a meter is called a
Nanometer
*****The speed at which waves travel is called
Velocity
The color in the visible spectrum with the shortest wavelength is
Violet
he separation of white light into its spectral components is
Dispersion
n reflection, the angle of incidence is equal to
The incident ray
What is the difference between specular and diffuse reflection
Specular reflection is a clear sharp imagine and Diffusion reflection the light
What is the formula for the index of refraction
Index of refraction = Speed of light in Vacuum (air)
Speed of light in substance
What does the index of refraction tell you
It tells us the amount by which light slows down in a given medium
What is the formula for Snell’s Law
N1 Sin 01= N2 Sin 02
9) Draw a diagram of refraction. Please include and label the incident ray, the refracted ray, and the normal. Depending on whether or not your refracted ray bends towards or away from the normal (that’s up to you), label which medium has the higher n value.
see notes
The study of optics can be divided into 3 parts
Physical Geometric Physiologic
****Physical optics
is primarily concerned with the nature and properties of light itself
****Geometric optics
is the branch of optics in which the laws of geometry can be used to design lenses that include spectacles (glasses), optical instruments, telescopes, microscopes, cameras, etc.
****Physiologic optics
deals with the mechanism of vision and the physiology and psychology of seeing
****There are 2 main theories about the nature of light
Wave Theory and Corpuscular theory
Wave Theory
Light is wavelike and spreads like ripples across a still pods
Corpuscular Theory
Light is composed of tiny particles, like water droplets shooting out of a hose
****Wavelength
Crest to crest or trough to through
The wavelength of a given wave is the distance from the crest (peak) of one wave to the crest of the next (or trough to trough)
****Frequency
is the number of wavelengths passing a given point in 1 second.
*****Formula of Velocity
V = F x Wavelength
The products of Frequency
The product of the frequency and wavelength is equal to the velocity (or speed) of light.
What the speed of light?
Whats the figured?
The speed of light in a vacuum is 186,262 miles per second or 3.00 x 10^8 meters per second.
****Speed of light in a vacuum
What is the speed of light in a vacuum?
186,262
Red light has the longest or Shortest Wavelength?
LONGEST Wavelength
****Violet has the?
SHORTEST wavelength
**** Longest to shortest wavelength ROY G. BIV
Red Orange Yellow Green Blue Indigo Violet
****(low energy) which one has
(high energy) which one has
Red 650-750 nm (low energy) Orange 590-650 nm Yellow 560-590 nm Green 500-560 nm Blue 470-500 nm Violet 380-470 nm (high energy)
****Medium
is any substance that light can pass through, such as gas, liquid, and glass
Bending Light
If light rays pass through a medium obliquely at an angle, they will be bent a little at the surface/interface of the two mediums. This bending of light is called refraction. The use of lenses to help people see better is based on laws of refraction.
****Direction of light ray Perpendicular
Light rays passing perpendicularly through a medium?
`If light rays pass through a medium perpendicularly, the speed of the rays will be altered but the rays will emerge along the same line on which they entered the medium.
****Normal
an imaginary line that is perpendicular to the surface of a medium
****Incident Ray
a ray of light entering a medium
****Emergent Ray ( refracted ray)
the same light ray emerging from the medium
****Angle of Incidence (i)
the angle that the incident ray makes with the normal, which is perpendicular to the surface of the medium
****Angle of refraction (r)
the angle the ray makes within the medium by its change of direction, or the angle that the refracted ray makes with the normal
****Reflection
Light rays can also be reflected upon hitting the surface of a medium. Reflection is light that is rebounded (bounces back) from a surface and thus changes direction
****Reflected ray/ Emergent ray?
the ray of light that is rebounded from the surface of a medium
****Angle of Reflection
The angle that the reflected ray makes with the normal
****Law of reflection
When light strikes a reflective surface, it will be reflected at an angle equal to the angle of the incoming light. In other words, the angle of incidence is equal to the angle of reflection
*****Specular Reflection
Light reflected from a smooth surface produces a clear image and is cal
****Diffuse reflection
If the surface is irregular, light is reflected at many different angles and the image is disrupted/matte. This is diffuse reflection.
****medium’s index of refraction
The ability of a medium to refract a ray of light is related to the speed that light travels through that particular medium. This is referred to as a medium’s index of refraction. This index is a comparison of the speed of light through a given medium to its speed through a vacuum. It is essentially a quantitative expression of the optical density of a medium.
****Index of refraction
speed of light in vacuum (air)_ _______________ speed of light in substance
N=
speed of light in vacuum (air)_ ______________________ speed of light in substance
For air, n,
186,262 miles per sec = 1.00 ______________________ 186,262 miles per sec
****Whats the Refractive Index of air
1.00
For water
For water, n = 186,262 miles per sec = 1.33 ——————————————— 140,000 miles per sec Therefore, the refractive index of water is 1.33
****Traveling at Lower density
When traveling from a lower density medium to a higher density medium (lower refractive index to a higher refractive index), the light ray will be bent towards the normal. n1 < n2, ray is bent towards the normal
****Traveling higher density
When traveling from a higher density medium to a lower density medium, the light ray will be bent away from the normal. n1 > n2, ray is bent away from the normal
****Snell’s Law (the law of refraction)
A fundamental law in optics that governs the refraction of light in a transparent medium. It tells us how the angle of incidence is related to the angle of refraction and the refractive index. It can be used to calculate the angle of the incident ray, the refracted ray or the index of refraction. Lens designs are based on this relationship. It is also the basis of all ophthalmic equipment, many ophthalmic tests, measurements, and protocols.
***The amount of refraction increases
The amount of refraction increases as the wavelength of light Decreases Shorter wavelengths of light (violet and blue) are slowed more which results in more bending than the longer wavelengths (red and orange)
Light Intensity
Measured in terms of candles, a standard dating from pre-electricity times. The light from a single candle falling on a surface at a distance of 1 foot illuminates the surface with an intensity of 1 candle per square foot (1 footcandle). If a light source produces 100 footcandles of light, the light will be as intense as 100 candles at exactly 1 foot from the source. 10 footcandles for ordinary indoor tasks 30 footcandles for reading 100+ footcandles for detailed work
****How many foot candles do you think the sun in
10K Foot candles
The illumination of light
the illumination of light on a surface is inversely proportional to it’s distance from the light source
Wavelength of light that the eye can see?
****Dispersion?
The Visible spectrum is actually the frangmentation of white light. When white light is separated into its spectral components, this is known as dispersion.
****How is light refracted?
Light rays are refracted as they pass through a medium at an oblique angle. This is because the oblique rays that are closest to the surface of the new medium will enter the medium first and thus be slowed down first.
****Refracted speed chart
****What causes the speed of light to increase or decrease?
It is the change in speed of the light ray as it enters the
When traveling from a lower density medium to a higher density medium (lower refractive index to a higher refractive index), the light ray will be bent towards the normal.
n1 < n2, ray is bent towards the normal
When traveling from a higher density medium to a lower density medium, the light ray will be bent away from the normal.
n1 > n2, ray is bent away from the normal
SEE IF THESE MAKE SENCE
?Increase the r = decrease the refractive power of the eye
?Reduce the r = increase the refractive power of the eye
new medium that causes the ray to bend.
So if light travels from air through some other medium, it will always be slowed down.
Light rays are refracted as they pass through a medium at an oblique angle. This is because the oblique rays that are closest to the surface of the new medium will enter the medium first and thus be slowed down first.
****Which way does a refracted ray bend when going from one medium to another?
When traveling from a lower density medium to a higher density medium (lower refractive index to a higher refractive index), the light ray will be bent towards the normal.
n1 < n2, ray is bent towards the normal
When traveling from a higher density medium to a lower density medium, the light ray will be bent away from the normal.
n1 > n2, ray is bent away from the normal
Which way does a refracted ray bend when ging from one medium to another?
