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8K Light @ AJHS NZ

Light

QuestionAnswer
absorb This means to ‘soak up’ or ‘take in’. If something absorbs light it soaks it up and does not let it back out.
Absorption Objects ability to take in light. The higher the absorption, the fewer colours are allowed through. Transparent objects absorb the least amount of EM waves, translucent objects absorb intermediate amounts of EM waves and opaque objects absorb most
amplitude distance from trough or peak to midpoint of wave
angle of incidence The angle between the normal and the ray of light hitting a mirror. (bc collision of photons against the interface is completely elastic)
angle of refraction Angle between the light ray and the normal as it passes from one transparent material into another.
Bioluminescent Objects Organisms That Produce their own Light
blue One of the three primary colours of light.
Camera Tool that acts similar to the eye, forming a real upside-down image in the back on film paper.
chromatic dispersion where white light (which is made up of all frequencies in the visible spectrum) is split by a prism
Colours of white light? red, green, and blue.
Concave Lens A lens that is fatter at the top and bottom and skinny in the middle. Used to correct near-sighted vision.
Concave Mirror A mirror that is curved inward like the inside of a spoon
concave mirror makes what kind of image? real, inverted EXCEPT when object is within focal distance, when they will make negative, virtual upright images
Cones Light-sensitive cells that detect colour.
continuous spectrum white light + prism = rainbow colours
converging lens makes what kind of image? real, inverted EXCEPT when object is within focal distance, when they will make negative, virtual upright images
Convex Lens A lens that is fatter in the middle and thinner at the top and bottom. Used to correct farsighted vision.
Convex Mirror A mirror that is curved outward like the back of a spoon
convex mirror makes what kind of image? virtual, upright
Cornea Transparent front of the eye that light enters.
crest part of waves pointing up
cyan Secondary colour made by mixing green and blue light (greeny-blue).
cyan light made from green light + blue light =
describe path of light in different mediums light wants to travel btw any two points in the shortest possible path for light in terms of TIME - whichever medium that light is faster, it will want to "spend more time there" so the light will bend in the same direction in the interface
diffraction when a wave moves through a small opening and bends around the corner of the opening, only significant if the size of the opening is on the order of the wavelength or smaller (smaller the hole, the greater the spreading)
Diffuse reflection Occurs and no clear image is formed. occurs from rough surfaces
dispersion The separating of the colours in light, for example when white light passes through a prism.
diverging lens makes what kind of image negative, virtual, upright
Electromagnetic Spectrum The complete range of electromagnetic waves placed in order of increasing frequency: long waves > radio waves > microwaves> infrared > visible light > ultraviolet > x-rays > gamma rays
Electromagnetic Wave a wave that is partly electric and partly magnetic fields and carries energy. Emitted by vibrating charges.
Farsighted The eyeball is too short so the image comes into focus behind the retina. Images far away are clear but nearby objects are blurry.
filter Something which only lets certain colours through and absorbs the rest.
Focal length The distance along the optical axis from the centre of a mirror to the focal point.
focal point the single point where light from horizontal rays is reflected by concave mirrors (or refracted by converging lenses) is focused and reflected outward from convex mirrors and diverging lens
focal point of plane mirror are infinite
frequency number of times persecond eg waves passing
Gamma Rays Electromagnetic rays that have the most energy, highest frequency and lowest wavelength. Gamma rays are the most penetrating of the EM waves and are used to kill cancer cells.
green One of the three primary colours of light.
Hologram A piece of film that produces a three-dimensional image of an object; made by using a laser light
How does light travel? It travels in waves in a straight lines called light rays.
How is a rainbow formed? when sunlight hits raindrops in the sky separating the light into a spectrum.
How will light reflect off a mirror? predictable angles
If the angle of an incoming light ray equals the angle of a reflected ray it is called what? The Law of Reflection
illuminated any visible object that is not a light source.
image A picture which forms in a mirror, or on a screen, or is made by lenses.
Incandescent Objects Make their own light because they are so hot they glow
incident ray Light ray hitting a mirror.
index of refraction n = c/v constant specific to a medium that helps describe the speed of light in that medium, always greater than 1, the larger the n - the slower light moves in that medium
Infrared rays The invisible low frequency electromagnetic waves you can feel. Infrared waves are longer than visible light but shorter than micro waves. These waves create heat and are used in heat lamps.
interface The boundary between two materials.
Interference A wave interaction that happens when two or more waves overlap that combine to form a single wave
Iris Ring of muscle that contracts and expands to change the size of the pupil. Gives the eye its colour.
laser Something which produces a narrow beam of light of one pure colour (short for Light Amplification by Stimulated Emission of Radiation).
law of reflection? The angle of incoming light ray equals the angle of reflected ray.
Lens A transparent object that refracts light waves, creating bending, such that they converge or diverge to create an image
light made up of photons that each represent an EM wave, has a dual nature bc it can act as a wave and a particle, approximated as a ray moving in a straight line
Light travels in a straight line until...................... it hits an object.
Light Year the distance light travels through a vacuum during one year.
luminous any object that produces visible light.
magenta Secondary colour made by mixing red and blue light (pinkish red).
magenta light made from red light + blue light =
magnification of lens M = -dimage/dobject = himage/hobject
Medium The material in which a wave travels.
Micro waves The radio waves with the shortest wavelengths and highest frequency. These waves are used to heat your food in a microwave oven and used for cell phones and in radar systems.
Microscope Tool that uses a combination of lenses to form an enlarged image of tiny objects.
Near-sighted The eyeball is too long and causes the image to come into focus before the retina. The near-sighted person can see nearby objects but distance objects are blurry.
Near-sightedness A condition in which the lens of the eyes focuses distant objects in front of rather than on the retina
Non-Luminous Objects do not produce their own light we see them because of the light they reflect
normal An imaginary line at right angles to a mirror, where a ray of light hits the mirror.
Opaque materials that absorb light without reemission and consequently do not allow light through them
Optic Nerve An image is transferred from the retina to the brain through this group of nerve cells.
particle theory applied to light energy transformation properties
penumbra a partial shadow that appears where light from part of the source is blocked and light from another part of the source is not blocked
photon. It is a tiny bundle of energy by which light travels.
Pigment A substance that gives another substance or a mixture its colour
plane Smooth and flat.
Plane Mirror A mirror that has a flat surface
Polarization the alignment of vibrations in a transverse wave, usually by filtering out waves of other directions
Primary colours of Light Red, Blue, Green
Primary colours of pigment Yellow, Cyan and Magenta
primary colours The three main colours which can make white light (red, green and blue).
prism solid figure with triangular ends and rectangular sides used to disperse light into a spectrum
Prisms job? It bends light by refraction into a spectrum of colours.
Pupil Opening through which light enters the inside of the eye.
Radiation Transfer of energy as electromagnetic waves
Radio waves Electromagnetic waves that have the longest wavelength and lowest frequency. Used for broadcasting radio and television signals.
ray A beam of light drawn on diagrams as a straight line, and showing which way it is travelling.
ray diagram A diagram showing the passage of light rays.
red One of the three primary colours of light.
red, green, blue make Primary colours of light
reflect Light bounces back from a surface instead of passing through it.
reflected ray The ray of light bouncing off the mirror.
Reflection The bouncing back of an object or wave when it hits a surface through which it cannot pass.
refract to bend
Refraction The bending of a wave as the wave passes between two substances in which the speed of the wave differs
refractive index air 1.3
refractive index glass 1.5
refractive index water 1.3
Retina Layer of cells inside the back of the eye that contains rods and cones.
Rods Light-sensitive cells that pick up small amounts of light.
scatter When light rays bounce off something in all directions.
secondary colours The colours made when two primary colours mix.
shadow A place where light cannot get to, because an opaque object is stopping the light.
source An object which creates something.
spectrum the complete range of electromagnetic wave frequencies and wavelengths
Telescope Tool uses mirrors and lenses to collect and focus light from distant objects.
total internal reflection if the angle of incidence is large enough, the entire amount of photons will be reflected at the angle of reflection and NONE will refract, occurs at the critical angle
Translucent Describes matter that transmits light but that does not transmit an image because it allows only some light to pass through
transmission the passing of light or other form of energy through matter.
transmit To send along or pass through.
Transparent Describes matter that allows light to pass through with little interference
trough part of waves sloping down
Ultraviolet Rays Electromagnetic waves shorter than visible light but longer than X-rays. They carry more energy than light and can cause skin cells to produce vitamin D. Too much UV exposure may increase risk of cancer.
Umbra the darker part of the shadow where all the light is blocked, eg a small light source produces a sharp dark shadow
visible light wavelength range from 390 to 700 nm (shorter wavelength is violet and longer wavelength is red). The main colours of visible light (in order of largest to smallest wavelength) are: red, orange, yellow, green, blue, indigo and violet.
wave theory applied to light reflection or refraction at the interference of 2 media
Wavelength The distance between two corresponding parts of a wave. The longer the wavelength, the slower the wave. The shorter the wavelength, the faster the wave.
What are transverse waves? They are waves that vibrate in a direction perpendicular to their motion.
What causes penumbras if there are many light sources around and if there are lots of objects
What colours have the longest wavelengths? red, orange
What colours have the shortest wavelengths? blue, violet
What medium can light travel fastest through? ( glass, air , water , vacuum) vacuum
What two types of energy are in light? magnetic and electric
Refraction, when light crosses into a new medium what happens to the frequency and wavelength frequency same, wavelength changes
Wavelengths are diffracted the most? the longer the wavelength, the more it is diffracted
white light made from red light + green light + blue light =
Why do grass and leaves appear green to our eyes? Chlorophyll absorbs some colours but scatters the green light waves which the human eye sees.
Chromatic dispersion explanation.. index of refraction for shorter wavelengths is greater than longer wavelengths in a given medium
X-rays Second shortest electromagnetic waves. They have more energy than UV and can penetrate most matter and is used to make images of bones inside the body. Too much can lead to cancer.
yellow Secondary colour made by mixing red and green light.
yellow light made from red light + green light =
secondary colours of light yellow, cyan, magenta
Created by: johncl