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8K Light @ AJHS NZ
Light
| Question | Answer |
|---|---|
| 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
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