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Light And Optics

Key Questions. What is light? How can we make light?Why are there different colors of light?How does light behave in a prism?. Let it glow, let it glow, let it glow. Take white board and keep white side facing up. Don't look at the bottom!When I say go, flip board over so white side is down. Plac

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Light And Optics

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    1. Light And Optics CPO Science Maybe something about the energy needed to create light being somewhat like the energy we get from eating that little cold cut dinner. You need energy from somewhere to produce light.Maybe something about the energy needed to create light being somewhat like the energy we get from eating that little cold cut dinner. You need energy from somewhere to produce light.

    2. Key Questions What is light? How can we make light? Why are there different colors of light? How does light behave in a prism?

    3. Let it glow, let it glow, let it glow Take white board and keep white side facing up. Don’t look at the bottom! When I say go, flip board over so white side is down. Place part of a hand over the square. Keep hand there! When lights go out, remove hand and observe.

    5. Charge it up with color Take out the red, blue, and green LED lights, plug them in, and use them to energize the phosphorescent paper Remove the colored lights and observe the paper with the room lights off How can you explain your observations?

    6. Light and Color How does a TV or computer monitor display many, many different colors when they start with only red, blue, and green pixels? Mix blue and green light. What color do you see? Mix red and blue light. What color do you see? Mix red and green light. What color do you see? Mix all three lights!

    8. Overview Simple Optical System (Beaker Funhouse) Reflection/Refraction in a Prism (Secret to Tic-Tac-Toe Invincibility and Prismatic Name Enlightenment) Critical Angle/Total Internal Reflection (Laser Proving Ground) We are going to begin this Investigation with Beaker Funhouse – This activity challenges the participants to exercise their observational skills on an interesting yet familiar optical system. Secret Tic-Tac-Toe invincibility – Can you believe your eyes with this mystifying example of counter-intuitive optical phenomena? Prismatic Name Enlightenment – We begin to refine our investigation by looking deeper at ourselves ( our names at least ) to better understand what we have observed and begin to see the light. Laser Proving Grounds – This is the experiment part of the investigation where we apply what we have observed and the ideas we have formulated to a testable system that will give us the information we need to tie it all together and make some real conclusions This Investigation puts the two concepts of reflection and refraction together and demonstrates their relationship in an optical system. We are going to begin this Investigation with Beaker Funhouse – This activity challenges the participants to exercise their observational skills on an interesting yet familiar optical system. Secret Tic-Tac-Toe invincibility – Can you believe your eyes with this mystifying example of counter-intuitive optical phenomena? Prismatic Name Enlightenment – We begin to refine our investigation by looking deeper at ourselves ( our names at least ) to better understand what we have observed and begin to see the light. Laser Proving Grounds – This is the experiment part of the investigation where we apply what we have observed and the ideas we have formulated to a testable system that will give us the information we need to tie it all together and make some real conclusions This Investigation puts the two concepts of reflection and refraction together and demonstrates their relationship in an optical system.

    9. What does Transparent mean? What happens? What are some examples of transparent materials? What is meant by the word transparent? Something that allows light to pass through it. Let’s think about what a transparent material is. What are some examples? ( air, water, glass, diamond, free space, diamonds and other gems, etc.) What do we observe that lets us recognize a transparent material? ( light passes through, you can see right through it ) Light passes through these materials. Think about standing in front of a store with a large plate glass window and what you would see. Sure, light is passing through, but what else do you see? ( light is also reflected, you would see your own reflection ). Let’s take a look at an optical system and observe what is going on. What is meant by the word transparent? Something that allows light to pass through it. Let’s think about what a transparent material is. What are some examples? ( air, water, glass, diamond, free space, diamonds and other gems, etc.) What do we observe that lets us recognize a transparent material? ( light passes through, you can see right through it ) Light passes through these materials. Think about standing in front of a store with a large plate glass window and what you would see. Sure, light is passing through, but what else do you see? ( light is also reflected, you would see your own reflection ). Let’s take a look at an optical system and observe what is going on.

    10. What Is an Optical System? Anything that involves light Used to study how light behaves An optical system is anything that involves light. This makes almost everything an optical system. We try to keep these systems as simple as possible to make it easier to understand what is taking place. In this case we are looking at how transparent materials influence the behavior of light. An optical system is anything that involves light. This makes almost everything an optical system. We try to keep these systems as simple as possible to make it easier to understand what is taking place. In this case we are looking at how transparent materials influence the behavior of light.

    11. Simple Optical System Observe the Beaker with the water and pencil in it Look at the Beaker from many different vantage points What strange or interesting things can you see involving the image of the pencil? BEAKER Funhouse, But where are the mirrors? Here we have a beaker filled with water that has a pencil sticking out of it. Take some good looks at this set up from a bunch of different vantage points or views and make some observations involving the image of the pencil. Do you see anything interesting or strange happening? Ask for people to call out the things they have observed, and/or ask who else has observed these and perhaps other aspects of the system. Here are some commonly made observations with explanations for you that you may need. Some groups may need to get more in depth at this point but for the most part we are simply making observations now. BEAKER Funhouse, But where are the mirrors? Here we have a beaker filled with water that has a pencil sticking out of it. Take some good looks at this set up from a bunch of different vantage points or views and make some observations involving the image of the pencil. Do you see anything interesting or strange happening? Ask for people to call out the things they have observed, and/or ask who else has observed these and perhaps other aspects of the system. Here are some commonly made observations with explanations for you that you may need. Some groups may need to get more in depth at this point but for the most part we are simply making observations now.

    12. OBSERVATIONS The pencil is bent There are two pencils There are three pencils The pencil is Magnified When you look straight down into the beaker, the pencil doesn’t seem bent The pencil seems bent by the water when looking through the side of the glass - The light coming off the pencil is being refracted by the water and the glass of the beaker, but primarily from the water. With the beaker being cylindrical in shape the amount of refraction depends on how much water you look through, so when you see the pencil from different angles there is a different amount of water acting on the image of the pencil and it will seem to change shape, look distorted and move around. There are two pencils- Light is bouncing off the pencil in all directions. Some light that comes out of the top of the beaker gets refracted to your eye, and some from the side gets refracted to your eye. We can’t really tell just by looking at the beaker what angles the light came off of the pencil, or the angles the light gets refracted when it leaves the beaker. What we do know is that it is getting to our eye because we can see it. Much in the same way that you may be able to take two totally different routes home from work, the final destination is the same. There are three pencils- In addition to the two pencil case, some observant people may also notice the reflection of the pencil off the bottom of the beaker. This would imply that both refraction and reflection are happening at the same time, which is true. Light is leaving the pencil and traveling in all directions, including down. Some of this light is leaving the beaker and being refracted as it does so. If you can see the pencil from below, then you know this is happening. However, not all of the light is being refracted by the beaker, some is being reflected. We know this because we can see the pencil. If light wasn’t getting to our eye, we wouldn’t see the pencil, but we do, so light is getting to us. The pencil seems magnified- This is due to the shape of the beaker. The beaker is acting like a convex lens, the same as you would find in a magnifying glass. What we see is the spread out light that forms an image that is larger than the pencil itself. When you look straight down the pencil doesn’t seem bent- When the light from the pencil leaves the water perpendicular to the surface of the water its direction is not altered by refraction. It is only when light is moving from one material into another ( water into air ) at an angle that the direction is changed.   The pencil seems bent by the water when looking through the side of the glass - The light coming off the pencil is being refracted by the water and the glass of the beaker, but primarily from the water. With the beaker being cylindrical in shape the amount of refraction depends on how much water you look through, so when you see the pencil from different angles there is a different amount of water acting on the image of the pencil and it will seem to change shape, look distorted and move around. There are two pencils- Light is bouncing off the pencil in all directions. Some light that comes out of the top of the beaker gets refracted to your eye, and some from the side gets refracted to your eye. We can’t really tell just by looking at the beaker what angles the light came off of the pencil, or the angles the light gets refracted when it leaves the beaker. What we do know is that it is getting to our eye because we can see it. Much in the same way that you may be able to take two totally different routes home from work, the final destination is the same. There are three pencils- In addition to the two pencil case, some observant people may also notice the reflection of the pencil off the bottom of the beaker. This would imply that both refraction and reflection are happening at the same time, which is true. Light is leaving the pencil and traveling in all directions, including down. Some of this light is leaving the beaker and being refracted as it does so. If you can see the pencil from below, then you know this is happening. However, not all of the light is being refracted by the beaker, some is being reflected. We know this because we can see the pencil. If light wasn’t getting to our eye, we wouldn’t see the pencil, but we do, so light is getting to us. The pencil seems magnified- This is due to the shape of the beaker. The beaker is acting like a convex lens, the same as you would find in a magnifying glass. What we see is the spread out light that forms an image that is larger than the pencil itself. When you look straight down the pencil doesn’t seem bent- When the light from the pencil leaves the water perpendicular to the surface of the water its direction is not altered by refraction. It is only when light is moving from one material into another ( water into air ) at an angle that the direction is changed.  

    13. Color Teaching Tool Slides This slide shows an example of two images from our Color Teaching Tools CD-ROM that is part of the teacher tool kit. This CD has printable images that can be used to make overheads, add to supplementary hand-outs, or some other use you may find. These images could also be displayed in the classroom during discussion or investigation to give students visual cues about the topic being discussed or investigated. There are 86 images in PDF format on the CD, roughly one per section, although there are some sections that we felt didn’t really need extra images and a few sections that have two. These images are not in the textbook or investigation guide, but we thought they could be helpful on some level. This slide shows an example of two images from our Color Teaching Tools CD-ROM that is part of the teacher tool kit. This CD has printable images that can be used to make overheads, add to supplementary hand-outs, or some other use you may find. These images could also be displayed in the classroom during discussion or investigation to give students visual cues about the topic being discussed or investigated. There are 86 images in PDF format on the CD, roughly one per section, although there are some sections that we felt didn’t really need extra images and a few sections that have two. These images are not in the textbook or investigation guide, but we thought they could be helpful on some level.

    14. Color Teaching Tool Slides An additional image from the CTT CD-ROM.An additional image from the CTT CD-ROM.

    15. Refraction/Reflection in a Prism See Page 112 in the Investigation Guide Handout for written directions Take out Prism from CPO Optics kit For full written instructions you can refer to page 106 in the Investigations guide. You will need a piece of paper and something to write with and the Prism from the CPO Optics kit for this activity. Draw a 5cm line on a piece of graph paper. Draw an X about 1 cm above the line and an O directly below the X and about 1cm under the line. Fold the piece of paper along the line so that it makes an angle of more than 90 degrees. With the long flat side of the prism laying flat on the paper, place the large glass prism down over the O and align one of the 45 degree angle edges of the prism with the fold. Look into the prism and move your head up and down to change the height that you look into the prism. What do you see? Does anything change? What is happening? Could this be used to ensure Tic-Tac-Toe invincibility? Have participants share the things they are seeing. For this part we are dealing with when the participants see either the X or the O. They will be able to see both, but we will deal with that situation later.For full written instructions you can refer to page 106 in the Investigations guide. You will need a piece of paper and something to write with and the Prism from the CPO Optics kit for this activity. Draw a 5cm line on a piece of graph paper. Draw an X about 1 cm above the line and an O directly below the X and about 1cm under the line. Fold the piece of paper along the line so that it makes an angle of more than 90 degrees. With the long flat side of the prism laying flat on the paper, place the large glass prism down over the O and align one of the 45 degree angle edges of the prism with the fold. Look into the prism and move your head up and down to change the height that you look into the prism. What do you see? Does anything change? What is happening? Could this be used to ensure Tic-Tac-Toe invincibility? Have participants share the things they are seeing. For this part we are dealing with when the participants see either the X or the O. They will be able to see both, but we will deal with that situation later.

    16. OBSERVATIONS I can see the X at first When I move my head up and down the X vanishes When the X vanishes the O takes its place This seems to be happening at the same angle, the “magic angle” What are you changing when your head moves up and down in height? You are changing the actual angle that you are looking into the prism. Can you describe what you are seeing? The X changes into the O and the O changes into the X. This point corresponds to a particular angle, and at this “magic angle” something is happening. This version of the experiment may not give us enough information to determine what exactly is happening, but by modifying the experiment we can try to get a little more information out of the system. We know SOMETHING is taking place, and we can try to explain it, so now let’s try to narrow down the possibilities. What are you changing when your head moves up and down in height? You are changing the actual angle that you are looking into the prism. Can you describe what you are seeing? The X changes into the O and the O changes into the X. This point corresponds to a particular angle, and at this “magic angle” something is happening. This version of the experiment may not give us enough information to determine what exactly is happening, but by modifying the experiment we can try to get a little more information out of the system. We know SOMETHING is taking place, and we can try to explain it, so now let’s try to narrow down the possibilities.

    17. Prismatic Name Enlightenment Repeat the process for the X and O but instead of the X write your first name. Also write your first name in place of the O but this time underline your name. What information do you now see that can help us explain what is going on? This Is an interesting modification of the activity in the Investigation Book that we came up with that adds a step to the inquiry based learning process. It is a good example of how the Investigations are flexible enough to allow changes to be made as you may see fit to use with your students. What happens at that “ magic angle “? At the same angle when the X changed into the O the name changes from right side-up to being upside-down. How can we tell we are seeing two different names? Because one is not underlined, and upside-down, we can tell that it is the other name and it has been reflected somehow. Can we tell if it was just refracted by the Prism? If it had simply traveled through the prism and then been refracted up to our eye, it would not be upside-down, it would be right side-up like the name beneath the prism. When it leaves the prism we know it gets refracted, but now we know one of the names has been reflected as well. So what can we say is happening? The point at which the reflected name stops leaving the prism and disappears, the refracted name begins to leave the prism and seems to take its place, and vice versa. This Is an interesting modification of the activity in the Investigation Book that we came up with that adds a step to the inquiry based learning process. It is a good example of how the Investigations are flexible enough to allow changes to be made as you may see fit to use with your students. What happens at that “ magic angle “? At the same angle when the X changed into the O the name changes from right side-up to being upside-down. How can we tell we are seeing two different names? Because one is not underlined, and upside-down, we can tell that it is the other name and it has been reflected somehow. Can we tell if it was just refracted by the Prism? If it had simply traveled through the prism and then been refracted up to our eye, it would not be upside-down, it would be right side-up like the name beneath the prism. When it leaves the prism we know it gets refracted, but now we know one of the names has been reflected as well. So what can we say is happening? The point at which the reflected name stops leaving the prism and disappears, the refracted name begins to leave the prism and seems to take its place, and vice versa.

    18. OBSERVATIONS I can see my name upside-down When I move my head up and down my name vanishes When my upside-down name vanishes the underlined name takes its place, and it isn’t upside-down any more This seems to be happening at the same angle, the “magic angle” What happens at that “ magic angle “? At the same angle when the X changed into the O the name changes from right side-up to being upside-down. How can we tell we are seeing two different names? Because one is not underlined, and upside-down, we can tell that it is the other name and it has been reflected somehow because we know from experience that when things are reflected the image is reversed Can we tell if it was just refracted by the Prism? If it had simply traveled through the prism and then been refracted up to our eye, it would not be upside-down, it would be right side-up like the name beneath the prism. When it leaves the prism we know it gets refracted, but now we know one of the names has been reflected as well. So what can we say is happening? The point at which the reflected name stops leaving the prism and disappears, the refracted name begins to leave the prism and seems to take its place, and vice versa.What happens at that “ magic angle “? At the same angle when the X changed into the O the name changes from right side-up to being upside-down. How can we tell we are seeing two different names? Because one is not underlined, and upside-down, we can tell that it is the other name and it has been reflected somehow because we know from experience that when things are reflected the image is reversed Can we tell if it was just refracted by the Prism? If it had simply traveled through the prism and then been refracted up to our eye, it would not be upside-down, it would be right side-up like the name beneath the prism. When it leaves the prism we know it gets refracted, but now we know one of the names has been reflected as well. So what can we say is happening? The point at which the reflected name stops leaving the prism and disappears, the refracted name begins to leave the prism and seems to take its place, and vice versa.

    19. Time to Experiment Use a Simple Model- Laser and Prism Build Upon What You Have Learned – This Magic Angle is Critical to what is going on What we need to do is find out why this is happening. Instead of using an image of a letter or a name, let’s use a bright and easily manipulated light source, like a laser to investigate what is happening to light as it moves through the prism. What we need to do is find out why this is happening. Instead of using an image of a letter or a name, let’s use a bright and easily manipulated light source, like a laser to investigate what is happening to light as it moves through the prism.

    20. Setting Up Laser/Prism Experiment See Page 113 in the Investigation Guide for written directions Take out Laser from CPO Optics kit Use Graph Paper we have provided For full written instructions you can refer to page 107 in the Investigations guide. You will need a piece of graph paper we have provided, something to write with and the Laser from the CPO Optics kit for this activity. Place the prism on its side in the center of the paper so that it looks like an arrow pointing to the right. Line up the long side of the prism with a vertical line on the graph paper and trace the prism. Place the laser on the left of the prism on top of the pre-marked outline “starting position”. Shine the laser at the prism and make sure the beam goes through and comes out the other side. As the laser shines upward at the top of the prism, trace the path of the beam as it leaves the laser and hits the prism, and where it exits the prism and continues on for a few centimeters. Repeat this process a few times by moving the laser itself up the page until you notice a dramatic change in the behavior of the exiting beam. Keep the beam directed at the prism so that it exits the prism at the same place for each trial. During each trial the beam will travel through the air and enter the prism. When this happens the direction of the beam inside the prism changes, and will be different than the direction of the beam in the air. This change of direction also occurs as the beam exits the prism and enters the air. This is the phenomenon of refraction. For full written instructions you can refer to page 107 in the Investigations guide. You will need a piece of graph paper we have provided, something to write with and the Laser from the CPO Optics kit for this activity. Place the prism on its side in the center of the paper so that it looks like an arrow pointing to the right. Line up the long side of the prism with a vertical line on the graph paper and trace the prism. Place the laser on the left of the prism on top of the pre-marked outline “starting position”. Shine the laser at the prism and make sure the beam goes through and comes out the other side. As the laser shines upward at the top of the prism, trace the path of the beam as it leaves the laser and hits the prism, and where it exits the prism and continues on for a few centimeters. Repeat this process a few times by moving the laser itself up the page until you notice a dramatic change in the behavior of the exiting beam. Keep the beam directed at the prism so that it exits the prism at the same place for each trial. During each trial the beam will travel through the air and enter the prism. When this happens the direction of the beam inside the prism changes, and will be different than the direction of the beam in the air. This change of direction also occurs as the beam exits the prism and enters the air. This is the phenomenon of refraction.

    21. OBSERVATIONS The exiting beam exits at a different angle for each trial When I move the laser up the paper, the exiting beam angles more in the downward direction At a certain point the exiting beam disappears This seems to be happening at the same angle, the “magic angle” What happens to the beam as it exits the prism? The beam gets bent or changes direction. Is there a pattern to how the beam seems to be changing. Yes. What is the pattern? With each trial the angle of the beam exiting the prism gets closer to the long, flat side of the prism. What dramatic change did you see in the path of the exiting beam? At one particular point, the beam is bent at an angle that matches the edge of the prism, and it actually does not exit but runs right along the inside of the prism, parallel to the side. You will notice that it no longer comes out the side of the prism like the other trials. The angle at which this occurs it called the CRITICAL ANGLE, ( not the magic angle ). What happens to the beam as it exits the prism? The beam gets bent or changes direction. Is there a pattern to how the beam seems to be changing. Yes. What is the pattern? With each trial the angle of the beam exiting the prism gets closer to the long, flat side of the prism. What dramatic change did you see in the path of the exiting beam? At one particular point, the beam is bent at an angle that matches the edge of the prism, and it actually does not exit but runs right along the inside of the prism, parallel to the side. You will notice that it no longer comes out the side of the prism like the other trials. The angle at which this occurs it called the CRITICAL ANGLE, ( not the magic angle ).

    22. Conclusions from Experiment At a certain angle the beam is refracted in a direction that doesn’t exit the prism This happens at a specific angle-The CRITICAL ANGLE When the angle is bigger than the CRITICAL ANGLE the beam experiences TOTAL INTERNAL REFLECTION What do you think is happening to the beam if it does not exit the prism? If you continue your trials you will notice that the beam of the laser no longer exits the prism but is actually reflected back into the prism. This is called TOTAL INTERNAL REFLECTION. This will occur at angles greater than the critical angle. What happens to the light from here? The light is reflected around the inside of the prism until it encounters a side that allows it to escape and be refracted. This will only happen if the angle at which it hits the side of the prism is less than the CRITICAL ANGLE. In the diagram on the slide, the light that gets internally reflected once then exits the prism the next time it meets the boundary of glass and air because this happens at an angle smaller than the critical angle. How does this relate to what we observed during the Name in the Prism experiment? We were observing the CRITICAL ANGLE. Light from the reflected name became totally internally reflected and seemed to disappear because the light no longer exited the prism and made it to our eye at the CRITICAL ANGLE. The light from the refracted name began to exit the prism at that point, and we began to see it. At all the angles we couldn’t see it, it was being internally reflected, and not traveling towards our eye. If you get down really low, you can actually see both names being reflected , one off the bottom of the prism and one off of the opposite side of the prism. What do you think is happening to the beam if it does not exit the prism? If you continue your trials you will notice that the beam of the laser no longer exits the prism but is actually reflected back into the prism. This is called TOTAL INTERNAL REFLECTION. This will occur at angles greater than the critical angle. What happens to the light from here? The light is reflected around the inside of the prism until it encounters a side that allows it to escape and be refracted. This will only happen if the angle at which it hits the side of the prism is less than the CRITICAL ANGLE. In the diagram on the slide, the light that gets internally reflected once then exits the prism the next time it meets the boundary of glass and air because this happens at an angle smaller than the critical angle. How does this relate to what we observed during the Name in the Prism experiment? We were observing the CRITICAL ANGLE. Light from the reflected name became totally internally reflected and seemed to disappear because the light no longer exited the prism and made it to our eye at the CRITICAL ANGLE. The light from the refracted name began to exit the prism at that point, and we began to see it. At all the angles we couldn’t see it, it was being internally reflected, and not traveling towards our eye. If you get down really low, you can actually see both names being reflected , one off the bottom of the prism and one off of the opposite side of the prism.

    23. How We Can Use Optics in Everyday Life Fiber Optics Laser Scanners Surgical Lasers Information Storage-CDs, DVDs High precision Distance Measuring How can we use TOTAL INTERNAL REFLECTION in useful tools for everyday life? Think about fiber optic cable, you may have seen examples of this material. It looks like a long solid tube of clear plastic or glass. If we were to shine light directly into this material from one end, what would happen? The light would travel down the fiber and exit the other end. Why doesn’t the light “ leak “ out or shine out the side? If the cable is thin enough and the light is shined straight into the fiber the light should move right down the fiber. What would happen if the fiber was bent? How does the concept of the critical angle impact this idea? As long as the light inside the fiber does NOT hit the side of the fiber at an angle less than the critical angle, then the light continues down the fiber. If it does, some will get out and some will be reflected. How can we use such a device? Light can be sent along these fibers to communicate information much the way wires are used. Pulses of light are used much the same way as pulses of electricity are used. Scientists and engineers have come up with ways to use fiber optics to carry much more information than a regular wire system is able to carry. What would you see if you looked down a fiber optic cable? You would see whatever light was entering the other side. Since just one fiber is very thin, not much light would shine into it in an everyday light level. But if a bunch of these cable were jumbled together you could look into the end and see the light coming in from the other side. Mechanics and doctors use just this kind of tool to look inside hard to get to places. Mechanics can see what may be wrong with the inside of an engine without taking it apart and doctors can check inside a human body without having to operate. Many other uses are being found for this type of exploratory scope. What other uses for fiber optics can you come up with? Surveyors measure distances with instruments that shoot out a beam of light and measure the time it takes for the light to return. They can get very accurate measurements of distance this way. They use a prism to reflect the light back to these Electronic Distance Measuring (EDM) devices. Scientists use this process to keep track of the distance of the moon from Earth with a prism- type reflector array set up by Apollo 11 mission 1969.How can we use TOTAL INTERNAL REFLECTION in useful tools for everyday life? Think about fiber optic cable, you may have seen examples of this material. It looks like a long solid tube of clear plastic or glass. If we were to shine light directly into this material from one end, what would happen? The light would travel down the fiber and exit the other end. Why doesn’t the light “ leak “ out or shine out the side? If the cable is thin enough and the light is shined straight into the fiber the light should move right down the fiber. What would happen if the fiber was bent? How does the concept of the critical angle impact this idea? As long as the light inside the fiber does NOT hit the side of the fiber at an angle less than the critical angle, then the light continues down the fiber. If it does, some will get out and some will be reflected. How can we use such a device? Light can be sent along these fibers to communicate information much the way wires are used. Pulses of light are used much the same way as pulses of electricity are used. Scientists and engineers have come up with ways to use fiber optics to carry much more information than a regular wire system is able to carry. What would you see if you looked down a fiber optic cable? You would see whatever light was entering the other side. Since just one fiber is very thin, not much light would shine into it in an everyday light level. But if a bunch of these cable were jumbled together you could look into the end and see the light coming in from the other side. Mechanics and doctors use just this kind of tool to look inside hard to get to places. Mechanics can see what may be wrong with the inside of an engine without taking it apart and doctors can check inside a human body without having to operate. Many other uses are being found for this type of exploratory scope. What other uses for fiber optics can you come up with? Surveyors measure distances with instruments that shoot out a beam of light and measure the time it takes for the light to return. They can get very accurate measurements of distance this way. They use a prism to reflect the light back to these Electronic Distance Measuring (EDM) devices. Scientists use this process to keep track of the distance of the moon from Earth with a prism- type reflector array set up by Apollo 11 mission 1969.

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