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Physics 8 Final
| Question | Answer |
|---|---|
| what is light | energy |
| what is a model | a way of representing something that we cannot see so that we can understand it better |
| what is a wave | a movement that transfers energy through matter or space |
| what is the medium | the matter that moves to transfer the energy (some kinds of waves do not need a medium) |
| what are the two kinds of waves? | transverse and compression waves |
| what is a compression wave? | the medium moves back and forth along the same direction as the wave (parallel) |
| what is a transverse wave? | the medium moves back and forth perpendicular to the direction of the wave |
| (Tor F) the medium travels with the wave. | false |
| what is the rest position | where the medium would be if it were still |
| what is the highest point of a wave called | crest |
| what is the lower point of a wave called | trough |
| what is the wavelength | the distance from one crest to the next (or trough) |
| what is the amplitude | from rest position to the crest or trough |
| what is frenquency | the number of times the wave repeats in a given period of time |
| a wave with high frequency has a ______ wavelength | shorter |
| a wave with a lower frequency has a _____ wavelength | longer |
| do waves with shorter or longer wavelengths transfer more energy? | longer. if they have the same amplitude the wave with the higher frequency has more energy |
| what is frequency measured in? | hertz (Hz) |
| what is refraction | the bending of a wave when it passes from one medium to another |
| what are the colours of the rainbow? | ROYGBIV |
| what is white light made up of? | all the colours of the rainbow |
| (T or F) each colour has a different wavelength and frequency | True |
| what happens to white light when it passes through a prism | it separates into the different colours of the rainbow |
| why do objects appear the colours they are? | because they absorb the other colours and reflect the ones that they appear to be |
| what happens to white objects? what colours are reflected or absorbed? | all colours are reflected |
| what happens to black objects? what colours are reflected or absorbed? | all colours are absorbed |
| what are the additive primary colours of light | red green blue |
| what happens when you mix red and green light | you get yellow light |
| what happens when you mix red and blue light | you get magenta light |
| what happens when you mix green and blue light | you get cyan light |
| what happens when you mix green red and blue light | you get white light |
| what are the secondary colours of light | yellow, magenta, and cyan |
| why are red blue and green called the additive primary colours of light | because they are the only colours you need to make white light |
| what colour bends the most in the spectrum | violet |
| what are light waves | electromagnetic waves |
| what is electromagnetic radiation | the transmission of energy in the form of electromagnetic waves |
| what is the whole range of electromagnetic waves called | the electromagnetic spectrum |
| what is the order from longest to shortest waves in the electromagnetic spectrum | radio wave, microwaves, infrared, UV rays, X-rays, Gamma Rays |
| what are radiowaves used for | broadcasting, radio, TV, aircraft and MRI scans |
| what are microwaves used for | telecommunications, radar, and microwave ovens |
| what are infrared waves used for | heat radiation, remote controls, and in computers to read CD ROMS |
| what are UV rays used for | your body needs them to produce Vitamin C, cause sunburns and suntans, black lights, killing bacteria, and for crime solving |
| what are x-rays used for | photograph bones and teeth, check machines for damage, and to check inside of baggage |
| what are gamma rays used for? | radiation treatment to kill cancer cells |
| restate the ray model of light | light always travels in a straight line |
| transparent materials | allows light to pass through freely and objects can be clearly seen through them |
| translucent materials | much of light passes through but is scattered. some light is absorbed or reflected. objects cannot be seen distinctly. |
| opaque materials | no light passes through. light is absorbed or reflected by the object |
| what is the normal | the line drawn at a right angles to a solid barrier such as a mirror |
| what is the incident ray | the incoming light ray to the barrier |
| what is the reflected ray | the light ray that bounces off the barrier |
| what is the angle of incidence | the angle between the incident and the normal |
| what is the angle of reflection | the angle between the reflected ray and the normal |
| what does the law of reflection state | the angle of incidence is equal to the angle of reflection |
| what happens when light passes from a less dense substance into a more dense substance | it slows down and bends toward the normal |
| what happens when light passes from a more dense substance into a less dense substance | it speeds up and bends away from the normal |
| what is the angle of refraction | the angle between the refracted ray and the normal |
| when you look at an object underwater, where does it appear to be? | above where the object really is |
| when light refracts in air what do you see? | a mirage |
| what characteristic does a substance need to have in order to reflect light? | it needs to be completely flat and smooth |
| what are the characteristics of an image produced by a plane mirror | right side up, same size as object, appears to be reversed left to right, |
| what type of mirror curves inward | concave |
| what does a concave mirror do to an image if it is far away | inverted and smaller |
| what happens to the image as it reaches the focal point of a concave mirror | flips and becomes large |
| what happens to the light rays in a concave mirror | they converge at a focal point |
| what is an example of a concave mirror | make up mirror |
| what type of mirror curves outward | convex mirror |
| what happens to the light rays in a convex mirror | they diverge |
| what does the image look like in a convex mirror | upright and smaller |
| what is an example of a convex mirror | passenger side mirror on a car |
| why do we use convex mirrors on the passenger side of a car | so that the driver can see more |
| what mirror is a concave lens like | convex mirror |
| what mirror is a convex lens like | concave mirror |
| in a concave lens what happens to the light rays | they diverge |
| what does the image look like in a concave lens | smaller and upright |
| in a convex lens what happens to the light rays | they converge at a focal point |
| what does the image look like in a convex lens | inverted and smaller before focal point, larger and upright at focal point |
| if the frequency increases the wavelength ______________ | decreases |
| where does light enter? | the pupil |
| what is the pupil | an opening into the eyeball |
| what is the coloured muscle surrounding the pupil | iris |
| what does the iris do | adjust the size of the pupil to allow the light amount of light in |
| what happens when it is dim out | the iris dilates the pupil |
| what happens when it is bright out | the iris contracts the pupil |
| what covers the iris and pupil? | the cornea |
| what does the cornea do | it is curved so it adjust to refract the light rays so that they can form an image on the retina |
| what is the white part surrounding the iriss | the sclera |
| what is behind the pupil | a convex lens |
| what is the lens | a convex lens that is flexible enough to change shape, does the final bit of focusing so that the image will form perfectly on the retina |
| what is the retina | a black screen at the back of the eye |
| what is the optic nerve | light rays are converged at the retina and convert into electrical signals which are sent to the brain |
| what happens to the lens when the object is far away | it gets thinner |
| what happens to the lens when the object is near | it gets thicker |
| what happens to light when it touches the retina | it forms an inverted image but the brain automatically flips it |
| what is the small area where there are no light-sensing cells called | the blind spot |
| what are the two main types of light detecting cells | cone cells and rod cells |
| what are cone cells | detect mainly three primary colours and their secondary colours, need lots of light |
| what are rod cells | detect shades of light and dark |
| what happens to the eye when people are near sighted | the eye is elongated so the light rays converge before the retina |
| how do we fix people that are near sighted | put a concave lens in front of the light rays to bend them apart a bit |
| what happens to peoples eye when they are far sighted | the eye becomes shorter than normal so the light converge after the retina |
| how do we fix people that are far sighted | put a convex lens in front of the eye to make the rays converge sooner |
| what is common as people age | their eye muscles weaken and they can no longer adjust the lens enough to focus on near by objects |
| what happens to the eye when people have astigmatism | the cornea has a distorted shape so that images are focussed on more than one place on the retina |
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