Active Physics Reflection and Refraction.wmv

if reflection is the bouncing of life and Sam refraction is the bending of light okay I want you to think about scenario let’s I know if you look out on the parking lot you might see a few people that like to go off-roading ok so they have a truck imagine this is off-roading instead of thinking this as light I want you to think of it as and graphs okay so somebody’s going to drive in with their truck and go from nice fast asphalt and then hit the grass well what’s gonna happen okay if you have this car hitting an asphalt what wheel is first going to hit the grass look the passenger side right the passenger wheel right here is going to the grass okay yes okay and the driver side wheels still going to be on the asphalt what do you think faster driving ask all the grass what’s faster asphalt right that’s gonna be faster so what you have is this you’re going to have one tire that’s going to be a lot slower and one tire that’s faster what would happen if you have once the entire solar one tire faster what’s going on that car it’s going to turn right it’s not going to spin all the way out what’s gonna happen is it’s going to go you have slow and fast you’re going to turn the car until that driver side wheel hits of hits the grass and then both are in the grass and it’s going to go the same speed does that make sense okay well that is taking that thing that happens with light so when you have a ray of light that comes in at an angle some of the rays are going to get bent firm are going to be slowed down first if this is glass and this is air or let’s say water okay what’s going to happen is some of the reason later going to get slowed down first you’re going to see an image event as it travels through that new surface so all the action happens right at the surface between a thinner and a thicker or vice versa that’s what we call a refraction all right I’ll pause again wait do we ever start yeah so that’s refraction right never paddle boat to see the or is going to be been some reason it’s just refraction okay and these areas are water is going to be thicker than air so you’re going from thinner to thicker it’s going to get bent inward okay it’s hard to tell this way it looks like it the other way and I’ll explain why hair cycle um but here are the three scenarios you need to know when an object goes dead on thinking and all three scenarios okay will I want you to think about your car tires hitting the grass if you go ahead on both tires hit the grass at the same time they’re both can get slowed down the same time they’re going to there’s a gunny no Benny so if you go in at zero degrees difference there won’t be any bed however if you go from there to the thicker at an angle you’re going to get bent inward and if you go from figurative thinner at an angle you’re going to get bent outward and I’m going to ask you these questions on the test okay I’m going to the you know it might be talking about index refraction what you’re going to talk about actually go just go to talk about thicker or thinner just think about car tires okay just think about the grass in the asphalt and I talked about thicker to thinner you know it’s going from grass to the asphalt if it goes from thinner to thicker that we’re talking about from the asphalt to the grass okay I’ll pull out this because it’s going to take a little while to copy here beaker into this corn oil what do you think is going to happen is it going to enlarge is it going to get smaller ohs are going to disappear in the thin air how we ready small here we go good what do you think so far disappearance cool yes oh you’re sorry to wake up for it yes we’ll do it again expand so much yes no here we go let’s try again ready so you got this you watching this time the Appetit she did it did it you see I’m writing don’t see

if they were both clear cool yeah yeah so you could do this as a party trick to take a glass take a glass you got to make sure it’s the same type of glass as this okay take a glass and your role in a towel shatter it up pour it in the in the oil and then have another glass that’s the same type and pull it out of the oil make it look like you put it back together magician secrets revealed all right oh yeah we’ll pause there I want you to copy these numbers down just say indices of refraction and these numbers here all right air the higher the number the slower the material or the slower light will travel yes I want to say indices of refraction and I want you to do air it goes one water he is 1.33 okay so here’s the deal air air is basement really that’s the same thing as going through vacuum okay or maybe is really like 1.000 three but we’ll just say one okay um so as the index of refraction gets bigger the light travels slow okay so the light going through a diamond is one is one of the slowest materials that light will travel tourism okay and it’s a whole lot slower I mean could think compared to water it’s almost twice as slow as as when light travels through water when light travels through air is one is more than twice it’s two and a half times slower when it goes through a diamond as it does go through air okay so light will travel slower when it goes through different substances okay um now so the reason that happened with the oil is because the index of refraction of the oil is equal to the index refraction of the glass for music so that’s why you don’t you can’t see the glass because they have the same index refraction so the legs not going to bend back and forth when it goes through cool huh yeah okay all right ah can’t move on we’re all wait I’ll wait you will pause Oh remember what I just said so think about that thing about that truck that’s going now from the grass to the asphalt okay so now we’re going from thicker to thinner all right now remember it bends away so if I haven’t going from from from the grass here when i get to the i’m going to turn away all right if I go a little bit further out I’m going to turn away more I’m gonna go further out i’m going to turn away more sooner or later because you’re going from you going to have a smaller angle than a bigger angle suitor you’ll get an angle here that’s going to cause that angle to be 90 degrees which means the lights going to get trapped along the surface okay we call that that causes this angle there okay to be 90 degrees so here’s your critical angle that causes this to be 90 which means the lights trap along the surface has anyone been um has anyone done any diving underwater yeah if you dive underwater and ever look up if you look up what you’re going to see you if you look straight up you’re going to see the boat above you get your see stuff outside the water but once you go past a certain angle it’s going to be completely dark it’s going to be a reflection going back into the water and the idea is this and then actually you can even do this if you stand next to a an aquarium a fish tank if you look into a fish tank and look up at the water there’s give me a certain angle we’re all set you’ll just see reflection back into the into the aquarium okay and what that is is looking past this critical angle because once you go past a critical angle critical angle waters about 48 degrees so I see everything and once I get it past 48 degrees then now is going to be just like a mirror and so there will be a circle around me that’s within the 48 degrees but as soon as I get past 48 degrees it’s going to be a mirror bouncing back in okay and I won’t be able to look outside that water okay you hit the critical angle the critical angle will cause that ray of light to bend all the way to 90 degrees so it’s

travel along the surface okay all right can I move on here again don’t copy work for okay once you get a general idea the critical angle causes the refracted angle to be 90 degrees so we’ll pause in I mean all the light is going to bounce back in okay so here we go here is a light beam that is going through glass and is bending is going from bigger than it is hard to see yeah I’m kind of like oh cool all right here’s a light beam it’s going this is glass right this a half moons blacks all right and as the beam of light exit the exits the glass is going from thicker to thinner it’s going to bend away okay so it was going in at 25 degrees and coming out at like 33 36 degrees like that yeah there’s a little bit is because nothing’s perfect and there might I don’t know there was like a if there’s something near there I don’t know but yeah there’s a big there’s imperfections with some of the stuff now here we’re getting close to that critical angle so again there’s some imperfections here some imperfections there okay so we’re at around the critical angle once and that’s about 38 degrees once you go to 50 degrees look what looks what happens the light is completely trapped and is getting completely reflected back down into the servants okay so that’s like the divers trying to look up all right once you go past an angle depending on the surface the thicker the serp the surface the smaller the angle but for water it’s about 48 degrees once you go past 48 degrees a Madison back in for this glass is about it was what about 40 degrees once you go past 40 it bounces back in and you get a reflection just like a mirror it’s gonna be just like a mirror with total internal reflection ok now this alone is very useful ok first off have you ever noticed a pool at 90 how it seems to like glow you know I’m talking about right here if you’re going to go to a pool at night all those lights are going to be on the side that’s prize for safety too but the idea is when you have a light on the side rays of light that are you know if they go up straight out they’re going to get the then the critical angle will be on escape but rays of light that go a little bit further out and get past a critical angle are now going to bounce back in circles so the reason it looks like that pool is trapping the light in is because it’s trapping the light in okay the light pass a critical angle has to bounce back into the water into the pools okay and that’s why these pools seem to glow at night because it’s keeping a lot of light from those from those light source it okay these are just couple of my pools of my summer home sure this is the Hamptons oh yeah after one handsome guy now this one the this is my I bluest my photo do you see the streams of green light coming through here what that is though they just have like little fountains that are spraying into the pool huh giggles but here’s the deal with these with these streams were these the water coming in what they have is a light here and because that extremist is thin enough the light is getting trapped notice how the lights coming from the ground over here and it’s trapped in the water as it goes in the pool okay so it’s going as it go to X as you go through that stream the light stays pass a critical angle and it keeps bouncing within the water so it doesn’t get to escape and now there is a little bit of escape because you can see the light but this is the idea of fiber optics okay do we know with fiber optics that you see like it Spencer’s a little plastic hair they shine a light and it comes out the other end it’s into Christmas trees too you know I’m talking about some Christmas trees have a fiber optic so that it is not a bulb they have to work out well the idea of fiber optics if any of you have fios the fiber optic signal okay I actually don’t know what the essence but i’m guessing signal alright what the idea was with fios is that’s the really high speed internet and with fios if you have a cable if you get your internet through cable what you have is a life you have a copper wire and you’re turning turn the electricity on and off on and off on and up and that’s fine that’s really fast but if with with that you can lose energy the longer the wire is

and it’s a little bit slower with turning on and turning off with cup with fios with a fiber optic cable what you have is there’s this tiny thin thin thin piece of glass that’s going to your house okay it basically there’s a guy from verizon on one and turning a light on and off oh gosh it’s a computer but you know you have a lights turning on and off from a verizon and because this glass is so thin okay the critical has always passed a critical angle and the light can never escape until it gets to the end and at the end they have a 90 degree cut off and they have a plug in the late like and finally escape okay that’s why I noticed these are good fiber optic cables notice how there’s no light escaping from the sides they only escape on the end okay this was my old job before I became a teacher before the teacher I worked for a company that had to run fiber optic cable and I like it was all of this all of this building so i had to connect from like AT&T to serve you know whatever is going to be eBay or something like that and when we ran the fiber optic cable you had to be really really careful because you know these were all insulated as you have all this insulation around it and if you ever dealt with any kind of wire you gotta strip a wire to put a ploy on it well what happens we strip the wire and we going to be extremely careful because you have this very very thin piece of glass and if you put your finger up to a fiber optic cable when there is no insulation on it when you put your finger up to it you would never feel the pressure on your fingertip the fiber optic cable go straight to your skin without you noticing until it hit a nerve and then you pull your finger back and you’d have a piece of glass stuck in your finger for a long time okay see you be really really careful with fiber optics because of this thin piece of glass and the other part was that when we ran the fiber could curb it or bend it too much because when you curb fiber for one its glass so if you curve it too much obviously it would break on the inside and you’re in trouble okay but the idea is that still even if you bend it enough where it wasn’t going to break you might be passed a critical angle I bet this came a little bit more here this light might be able to go within the critical angle and actually escape okay so you have it different types of fiber optics have different turn radiuses to it to make sure you don’t lose the signal but this saves a lot more energy then say using a copper wire okay diamonds same thing with diamonds okay this is a diamond this is like court with a diamond the read again we said the index of refraction of diamond was 2.42 is really really high where quartz or glass and maybe around 1.5 okay so glass will not trap light as well as a diamond if you put two if you put a diamond and a piece of glass next to each other and they have them cut the same way the diamond will just seem to glow like it has so much more light trapped in it than glass whoa and the reason that’s the case is because again it’s traffic light in okay with a diamond you’ll have light coming in from the top and maybe it tries to escape through the bottom but it’ll be past a critical angle and it’s going to bounce away then it hits over here again it’s past the critical angle and it reflects out of flex back in so diamonds the four C’s for diamonds are cut clarity carat and color cut is important okay the way you can cut a diamond might help with getting more critical angles so that more the diamond is more the light it’s gonna be trapped inside that done okay alright this is how a mirage works i want you to think about a mirage you’re going to fourth of july parade okay you look way off of the distance at the band coming down and you see on the ground it looks like water okay I’m or the car too version of it you’re out the desert you look far far away and then way out in the desert you see this beautiful blue water right you run towards the water as you get closer to the water it disappears it was a mirage right this is just like you looking out from water or the diamond or the pool but in this case what you have is on the surface of that sand okay you’re going to have really really hot water on that hot day or or on the road you’re looking at the parade because the asphalt is going to be so hot you’re going to get much hot much hotter air right along the bottom of the ground okay right along stand right up

right along the asphalt alright so what you have is you have really really hot air and a little bit cooler air so you have thicker substance and thinner substance so just like the water trying to escape the pool now it’s upside down the rail light now is trying to escape into the thinner air but it’s going to be passed a critical angle ok when you it only happens we look really far away at a really high angle right you’re looking past critical aim so the reflection bounces back up so if I’m standing here I think I’m looking at water down below what am I really seeing what’s what’s beautiful blue that I’m really looking at the blue sky so a mirage is just a reflect this is also how a prism works and how you get rainbows we all know right Isaac Newton’s want to found out that Wayne Wayne is really all the color we found out that each rate of light each color Ben’s differently so when white light travels through glass red will fan just a little bit orange will ban just a little bit more okay yellow a little bit more green a little more blue indigo violet so vile it bends light or refresh ask a lot more than red dose so the reason that you can get a rainbow is that as glass travels through and you know they make it a triangle to help this when you get that refraction the red light won’t Bend as much as the viable and it gets spread out so that’s how a prison works i’ll let you copy that polarizing lenses lastly i want to talk about i’m going to turn the lights on guys what another trick to impress the ladies for the night ok here we go polarizing lenses there are certain things out there that can polarize um where is my me you know what I mean say this guy had in the air likes hanging do you need that go and they bought a party didn’t touch the floor yet so they the other parking remember what it was like slow motion so demands ok um here please light is a wave right but light isn’t just a way that goes in one direction okay when light comes off from the electrons and all that stuff it goes in all different directions it’s all the planes so here’s one plane ok here’s another plane but light comes out and all the planes they’re going everywhere ok those look like this and this is what glarus every if you look at the water here you know if you were fishing you look at the water here at the beach and you look out on the water you get the reflection of the Sun you get all these planes reflecting out and it’s hard to see ok so what you want to do is you want if something only lets one plane in ok I only want this part of that light in not all these planes that are coming in every direction that make sense ok so what we do is we have polarizing lenses you can let go thank you it’s okay okay all right so um I know the first time I saw was for fishermen because with fishermen they’re gonna be looking at in the water line when they want to look in the water they want to look in the water they don’t want to see the glare on top so they were selling polarizing lenses on but now most good sunglasses are you buy a good pair of oakleys you’re going to have polarizing lenses on ok and the idea what polarizing lenses versus cheap lenses is that this is a polarizing lens and it’s not that it’s just darken but instead just like the slinky lights coming all the directions and I’m only going to get to let one of the planes in I’m only going to let the play of light going up and down in ok and it’s hard to tell with just one polarizing lens what it is in it but it does help get rid of glare any photographer will need a polarizing lens ok the polarizing lens gets rid of the glare all right but of course if you have sunglasses some some window tints will be polarizing all right now here’s the deal here’s a way to find out if you have good sunglasses or if you have 799 7-11 sunglasses ok polarizing here we go so you’re doing if I have a polarizing lens and I put another one in front of it it’s going to be a little bit darker but they’re

parallel right now ok so I have this and then I took another lens and do that so still that plane going up and down it’s going to be loud through however if i turn the lens and now it’s perpendicular so now i have this and i did that and now the waves will not be able to go through ok so again i turn cool huh yeah rose house so if you want to see if your glasses we’re actually polarizing or not you can do this you can take you know if you could if if you see something that’s advertised as polarizing sunglasses take two pairs and just do this and if you can see through the whole time that you spin it then those are not polarizing glasses okay yeah and you have fake Lee’s not oh please now with that have you ever noticed my mother-in-law I remember number of times where she was filming one of my kids around and then she can you say my camera’s broken because she would feel like this chase him I had my son around and then she tried to take a picture like that and she couldn’t see the picture anymore on the camera and I told her to take off her sunglasses okay because it what the problem was the light coming off is a lot of displays only come in one plane and when you wear sunglasses and you turn it your sunglasses are filtering out and you’re not able to see anything have you ever noticed in your car you’re driving your car you look at your car stereo and you have to tilt your head to see the display in the car stereo a lot of a lot of displays are only coming off on one plane if you wearing sunglasses their polarizing you’ll have to turn your head because you might be looking at 90 degrees or in block you what you see have you seen the checkerboards on the glass when you’re driving have you ever noticed when you drive along with newer cars you’ll look out the window and if you’re wearing sunglasses their polarizing you’ll see like this checkered pick pattern on the glass again there’s polarized the glass is somewhat polarized and of course its checkered it’s got to have 22 group two angles because if you had polarizing glass just going one direction and you turn your head the wrong way you won’t be able to look outside the glass and that would not be good okay but even with your cell phone you might look at your cell phone and especially with some of the cheaper cell phones the display might only be in one direction so if you look at your cell phone you might have to turn it because your sunglasses on okay all right last thing that I think is kind of cool with it I have these two they’re blocked if I take a third lens and I stick it in between watch this so if you can turn the other one in between so you can see the light I’ll turn the light off here see that this one’s in between the other two there you go cool huh so there’s polarizing lenses all right