Physical Science Chapter 22 - Light and Optics

Luminous Object

an object that is producing visible light

Illuminated Object

an object that is visible because it reflects light from an external source

Incandescence

light produced by objects that glow as a result of high temperature

Fluorescence

occurs when a material gives off visible light after absorbing EM energy (constant flow of EM)

Phosphorescence

similar to fluorescence but slower - material glows for a long time after absorbing energy (only absorbs energy once)

Chemiluminescence

chemical reactions that give off energy in the form of light

Bioluminescence

some living things can give off light using chemiluminescence

Ray

a model of light in which the endpoint represents the light's source and the light travels in one direction

Transparency

a material through which light passes without scattering, transmits a clear image - Does not transmit all wavelengths of light equally (color filters)

Translucent Material

a material through which light passes but the light is scattered and does not transmit a clear image

Opaque Material

a material through which visible light cannot pass

Light

light enters your eyes directly from a light source or when it is reflected from an object

Primary Color

one of the three colors of visible light that the human eye can sense; mixed to produce other colors

Secondary Color

a color of light that is produced when primary colors are mixed

Additive Color

a color that is produced by combining the wavelengths of different colors

Subtractive Color

a color that forms because of pigments absorbing some wavelengths of light that strike an object

Pigments

substances that absorb some wavelengths of light and reflect others

Diffuse Reflection

the reflection off a rough surface or an uneven surface that reflects light rays in all directions

Specular Reflection

reflection that occurs when a smooth surface reflects light rays in mostly the same direction

Incident Ray

a light ray approaching a reflective surface

Reflected Ray

the outgoing ray

Law of Reflection

the angle of incidence and the angle of reflection are equal and this holds true for both specular and diffuse reflections

Plane Mirror

a flat mirror

Virtual image

an image produced by diverging waves, formed at the point from which the diverging rays would have originated

Real Image

an image that forms at the point where converging rays of light intersect

Concave Mirror

a curved mirror with the reflected side on the inside of the curve

Focal Point

the point on an optical axis at which all reflected or refracted light rays from incident rays that are parallel to the optical axis converge

Focal Length

the distance from the focal point to the mirror's center of curvature

Convex Mirror

a curved mirror with the reflective side in the outside of the curve - Objects in convex mirrors appear smaller than objects that they reflect, and the reflected image includes more background area

Index of Refraction

a measure of how much a material will bend, or refract, light that enters it

Total Internal Reflection

a phenomenon that occurs at the boundary between two media when a light ray's angle of incidence exceeds a critical value, resulting in the ray being reflected back into the first medium instead of passing into the new

Lens

a disk of transparent material that refracts light to produce a real or virtual image

Converging Lens

collects incoming rays of light and focuses them at a point - Used to correct farsightedness because the light that enters a far-sighted person's eyes does not converge enough, producing sharp images.

Diverging Lens

spreads rays apart - A nearsighted person's eye converges too early, creating a blurry image.

After-Imaging

due to the opponent-color theory, the colors red and green will move through the same pathway, and the colors yellow and blue will travel along the same path.

Refracting Rays

slow —> fast (bends away); fast —---> slow (bends towards)

Speed of Light

c = 𝝀f, where c = 3 x 10^8

Energy of Light

E = hf (or hc/𝝀), where h = 6.63 x 10^-34

Snell's Law

n1sin 𝜃 = n2sin 𝜃 - n(1) and n(2) are indexes of refraction

How much of the EM spectrum is occupied by visible light?

2%

Rods

take over in dim light and don’t provide color vision or acuity

Cones

take over in bright light and provide color vision and acuity

What are the primary colors (additive)?

Red, green, glue - generated light

What are the secondary colors (additive)?

Cyan, magenta, yellow, and black - reflected light

What are the primary colors (subtractive)?

Cyan, magenta, yellow - used in color printing

What are the secondary colors (subtractive)?

Red, green, blue - produced by mixing primary subtractive colors.