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## AP/Calculus-Based Physics:Nature and Behavior of Light Units

Optics ("appearance" in ancient Greek) includes the behavior and properties of light and its interaction with matter. The study of optics includes understanding the behavior of visible, infrared and ultraviolet light. Because light is an electromagnetic wave, these events occur in X-rays, microwaves, radio waves, and other forms of radiation. Optics is also electromagnetism that can be described by the quantum nature and electromagnetic description of light.

### Behavior of Light (8)

#### Lesson Plans:

If your students think studying optics would be boring, wait until they try building their own spectroscopes and watching light refract through Jello Jigglers.  This resource is a set of 16 low-cost lesson/labs designed as an overview of the behavior of light.  For the 9th grade physical science class, try the explorations on light spectra, reflection, and refraction.  For more advanced students, we suggest the labs on diffraction, polarization, and fluorescence.  The lens labs would be appropriate for both.

This high-quality, standards-based classroom project explores the interaction of light with particles found in sunscreen.  The student task is to learn about absorption and reflection of ultraviolet light, design a computer model for an improved sunscreen that would contain zinc oxide nanoparticles, and create an ad campaign to promote the product.  Included materials are lesson plans, syllabus, Power Point lectures, student guides, free computer modeling software, and assessments. **NOTE: May be taught as a short mini-unit or as a two week project.

#### Activities:

This page contains a short explanation and Java simulation of the physics behind rainbows. It explores the reflection and refraction effects of light inside a water droplet as well as polarization.  A discussion forum regarding this material is also provided.

When light waves travel from one substance or medium into another, the waves may undergo a phenomenon known as refraction, which often looks like a bending of the light.  In this high-quality tutorial, students can explore how light behaves as it is refracted through a variety of mediums.  At the same time, they will learn about Snell's Law and form better understanding of the math behind the Index of Refraction.  Three Java simulations make the learning fun.

#### References and Collections:

This is an easy-to-read time line of milestones in optics, highlighting contributions of key people in the field.  It begins with the investigations of the early Greeks, progresses through early telescopes and microscopes, and continues the journey from ray optics and wave optics through the revolutionary advances of the 20th Century.

Try this great web site for a very broad selection of activities and background information on the science of light.  Your students can look at 12 optical illusions, play around with dozens of interactive simulations related to light behavior, and find scientific definitions of all the vocabulary associated with light and optics.  There is a full section devoted to teachers, with lesson plans and background information on color, light reflection and refraction, rainbows, geometric optics, human vision, and the wave nature of light.

#### Student Tutorials:

An award-winning set of tutorials created by an astronomer to give beginning students a brief overview of astronomy's place in the scientific endeavor.  The section linked here on electromagnetic radiation is a well-sequenced resource that helps the student see that light can behave as both a wave and a particle.

Is light a particle or a wave?  Well, it has characteristics of both.  This is the best tutorial we have found to introduce high school students to the wave-particle duality of light.  They can play with four simulations to see how a beam of light behaves when it is refracted, diffracted, and combined in a double-slit experiment.  Don't miss the simulation on reflection:  an excellent comparison of wave and particle theories that adolescent learners can comprehend.

### Ray Optics -- Reflection and Refraction of Light (21)

#### Lesson Plans:

A collection of more than 50 hands-on  experiments designed to introduce high school and middle school students to geometric optics, also known as the ray model of light.  Topics include reflection, refraction, pinhole cameras, the human eye, color and the visible spectrum, optical equipment, and ray streaks.  Each lab has background information, safety guidelines, and tips for use in the classroom.

Not sure whether to use a ray box or another light source for your geometric optics experiments?  This web page, by the authors of Practical Physics, gives advantages of both for varying lab situations.

This is an award-winning module created specifically for use with the PhET simulation Geometric Optics.  It includes a lesson plan with step-by-step printable student directions, background information on convergent lenses, and a full set of Power Point clicker questions (with answers) for formative assessment.  We suggest using it after students have explored concave/convex lenses in a hands-on lab (see Practical Physics Optics Labs above).

Total Internal Reflection, the principle behind fiber optics, is a phenomenon that occurs when a ray of light strikes a medium boundary at an angle larger than the critical angle.  This lesson plan helps students discover this phenomenon for themselves, with the use of a refraction tank.  The lesson is part of the SERC service, a collection of proven pedagogic methods for science education.  Allow one class period.

#### Activities:

These animations were developed by the author of the respected Physics Classroom web site to help students comprehend reflection and refraction.  Each one is accompanied by a full text explanation and links to additional resources on geometrical optics.

This resource can double as a tutorial and student activity in the computer lab.  The students interactively explore the Law of Reflection, concave/convex mirrors, and how surface texture affects the way light is reflected.  Try teaming it with the lesson plan above: "Mirror, Mirror On The Wall".

A great follow-up simulation after doing a classroom lab on converging lenses.  Your students choose from four "objects" (pencil, star, smiley face, and arrow).  They can change the curvature of the convex lens, adjust the focal length, and move the object to get a feel for how light refracts through a converging lens.  Don't miss the step-by-step lesson and Power Point clicker questions created by a high school teacher specifically for use with this simulation (see Lesson Plans above).

A very well-designed problem set by the PhET team, intended specifically for use with the simulation Geometric Optics (see item directly above).  It contains a two-page student guide with explicit directions on using the settings within the simulation.  It ends with a 10-point assessment to gauge student understanding of light refraction through a convex lens.

Students experimenting with pinhole cameras are often amazed to see an inverted image at the back of the box.  Often, they are confused about why the pinhole image is upside down, but we see things rightside-up with our eyes.  The difference is that the pinhole actually projects rays of light  through the hole to specific points on the back of the box. The lenses in our eyes act to converge light rays together into a common focus.  This lesson is a great springboard to help students understand the ray model of light.  **NOTE:  Pinhole camera can be constructed by the student.  See the resource directly below for step-by-step directions on building one out of an oatmeal box.

A pinhole camera is a camera without a lens.  It lets light into a sealed box through a tiny aperture (pinhole) that projects an inverted image onto photo-sensitive paper.  Virtually any container capable of excluding light can become a pinhole camera.  This resource gives explicit directions on how to build one out of an oatmeal box, take photos with it, and even develop them in a darkroom.  Experiments with pinhole cameras help students see how a beam of light projects from a point source to a particular spot.  The accumulation of all the rays passing through the pinhole forms an image at the film plane.  This is a basic principle of the ray model of light.  Did we mention it's fun because the camera really works?

A very simple yet enlightening simulation for exploring the function of a pinhole camera.  The applet draws lines from five points on a source through the pinhole.  Students can see the path of each ray of light and the resulting inverted image.  We suggest letting students play with this applet AFTER they have completed one of the labs above on pinhole cameras.

#### Content Support For Teachers:

This resource offers comprehensive background information on the nature of lenses and their refractive properties.  Accompanying ray diagrams provide valuable tools for understanding how images are formed by both converging and diverging lenses.   Sample problems and solutions relating to the mathematics of lenses are provided, along with a brief self-guided quiz.

In this item devoted to the physics of sight, the author explores how the human eye is able to refract light to produce a focused image.  The inclusion of lens and magnification calculations focuses the material specifically for the physics teacher.

This is an exemplary tutorial for introductory physics students, integrating background information on light reflection with four Java simulations.  Students can interactively investigate the Law of Reflection, concave and convex mirrors, reflection from smooth and rough surfaces, and total internal reflection.  We highly recommend it to supplement labs on reflection.

#### Student Tutorials:

In this beginning tutorial, the ray nature of light is used to explain how light reflects off both planar and curved surfaces to produce images.  Flash animations help the student understand properties of geometric reflection produced by plane, concave, and convex mirrors.

This beginning tutorial explores the conceptual and mathematical principles governing the bending of waves as they cross the boundary between two media.    Refraction principles are combined with ray diagrams to explain how lenses produce images.

When light waves travel from one substance or medium into another, the waves may undergo a phenomenon known as refraction, which often looks like a bending of the light.  In this high-quality tutorial, students can explore how light behaves as it is refracted through a variety of mediums.  At the same time, they will learn about Snell's Law and form better understanding of the math behind the Index of Refraction.  Three Java simulations make the learning fun.

A bi-convex thin lens is the type of lens used in eyeglasses, magnifying glasses, and single-lens cameras.  They work in accordance with simple principles of geometry.  This simulation-based tutorial lets students move the virtual lens back and forth on an optical axis.  They can observe the effects of the changing distances on the magnification produced by the lens.  The text tutorial further explains the fundamentals to prepare students to solve problems involving focal length and magnification.

A great companion tutorial to the item directly above.  This simulation by the same author lets students change the object size and focal length to see how these variables affect the image formed by a bi-convex lens.  The lens equation is displayed at the same time: values automatically change with the changing variables.

#### Assessment:

This web site offers exceptional interactive homework problems for beginning physics students.  This one presents them with three mirrors, with light hitting the first mirror at an incident angle of 62 degrees.  Given only a few angle measures, students must use geometry and the Law of Reflection to solve the problem.  A Socratic-Dialog "help" sequence guides students through each step, from conceptual analysis through the actual mathematics.

This is a companion homework problem to the one above, created by the same author.  Here is the scenario: A distant object forms an image 2.8 meters in front of a curved mirror.  With only this information, students must figure out the radius of curvature of the mirror.  This problem also contains ray diagrams to help students visualize the situation as they are guided through each step of the problem-solving.

### Microscopy and Optical Devices (8)

#### Lesson Plans:

Experiential Learning Module: 4-day                                               Grades 11-12
This module is a great way for students to apply their knowledge of the composition of light and measurement of light intensity.  Student teams design and build their own spectrographs, researching and developing a ground-or-space-based mission using their creation.  The authors provide lots of background support, with printable worksheets and troubleshooting tips.

#### Activities:

Students experimenting with pinhole cameras are often amazed to see an inverted image at the back of the box.  Often, they are confused about why the pinhole image is upside down, but we see things rightside-up with our eyes.  The difference is that the pinhole actually projects rays of light  through the hole to specific points on the back of the box.  Lenses, which we have in our eyes, brings light rays together into a common focus.  This lesson is a great springboard to help students understand the ray model of light.  **NOTE:  Pinhole camera can be constructed by the student.  See the resource directly below for step-by-step directions on building one out of an oatmeal box.

A pinhole camera is a camera without a lens.  It lets light into a sealed box through a tiny aperture (pinhole) that projects an inverted image onto photo-sensitive paper.  Virtually any container capable of excluding light can become a pinhole camera.  This resource gives explicit directions on how to build one out of an oatmeal box, take photos with it, and even develop them in a darkroom.  Experiments with pinhole cameras help students see how a beam of light projects from a point source to a particular spot.  The accumulation of all the rays passing through the pinhole forms an image at the film plane.  This is a basic principle of the ray model of light.  Did we mention it's fun because the camera really works?

A very simple yet enlightening simulation for exploring the function of a pinhole camera.  The applet draws lines from five points on a source through the pinhole.  Students can see the path of each ray of light and the resulting inverted image.  We suggest letting students play with this applet AFTER they have completed one of the labs above on pinhole cameras.

What do scientists see under a scanning electron microscope (SEM)?  Find out first-hand in this award-winning Java applet.  Students can choose from 14 specimens, including a cockroach, jellyfish, gecko foot, pollen grain, and more.  They will first adjust the focus, contrast, and brightness of the specimen to optimize its appearance.  Then they control a slider to increase the magnification in steps.....up to 10,000 times.  This activity would work well in the computer lab or in a classroom digital projection system.

#### References and Collections:

This site is a large collection of high school and middle school curricular materials on optics and microscopy.  Users can link to comprehensive tutorials on basic microscopy, digital imaging, optical microscopy, and more.  Text information is supplemented with innovative Java-powered virtual microscopes that allow users to explore focus, magnification, and translation in a real-life manner.

#### Student Tutorials:

How does a simple lens work?  This interactive, voice-narrated tutorial gives beginning students an introduction to both concave and convex lenses.  It provides detailed diagrams of how they refract light, converging or diverging the beam depending upon the shape of the lens.  Included are self-guided question-and-answer sets.

This Java-based tutorial introduces students to concave and convex lens characteristics and explains how each type of lens works to produce convergence or divergence of light.  It would be a great warm-up activity before a class lab on lenses and magnification.

### The Wave Nature of Light (5)

#### Activities:

Students often think of "light" only as that which the human eye can perceive.  This excellent resource introduces students to the entire electromagnetic spectrum (which,  of course, includes visible light.)  Students view models of photon emission/absorption, create a model photon beam, and interactively explore how light intensity is related to the frequency of light.

Most of us see examples of light wave interference every day without realizing it: the thin film of a soap bubble, reflections from the surface of a compact disc, and the wings of a diamond beetle.  This tutorial uses simple models to introduce students to constructive and destructive interference patterns.  The section on Young's double-slit experiment is especially well done.  Appropriate for high school physics.

Scientists began to question the classical theory of light as a particle when they studied the phenomenon of diffraction:  the bending of light around an obstacle into a "shadow region".  If light consisted only of a particle nature, it would not be capable of such movement.  This interactive tutorial helps students understand light scattering and diffraction through a single slit.

#### Student Tutorials:

How do we know that light behaves as a wave as well as a particle?  Young's classic double-slit experiment demonstrated the concept more than 200 years ago, establishing the wave theory of light.  This interactive tutorial is an excellent introduction to the wave nature of light.  It explains Young's experiment in a coherent way and includes voice narration, especially helpful for students with disabilities.

Is light a particle or a wave?  Well, it has characteristics of both.  This is the best tutorial we have found to introduce high school students to the wave-particle duality of light.  They can play with four simulations to see how a beam of light behaves when it is refracted, diffracted, and combined in a double-slit experiment.  Don't miss the simulation on reflection:  an excellent comparison of wave and particle theories that adolescent learners can comprehend.

### Electromagnetic Radiation and the Spectrum (7)

#### Lesson Plans:

This high-quality, standards-based classroom project explores the interaction of UV light with particles found in sunscreen.  The student task is to learn about absorption and reflection of ultraviolet light, design a computer model for an improved sunscreen that would contain zinc oxide nanoparticles, and create an ad campaign to promote the product.  Included materials are lesson plans, syllabus, Power Point lectures, student guides, free computer modeling software, and assessments. **NOTE: May be taught as a short mini-unit or as a two week project.

Experiential Learning Module: 4-day                                                       Grades 11-12
This module is a great way for students to apply their knowledge of the composition of light and measurement of light intensity.  Student teams design and build their own spectrographs, researching and developing a ground-or-space-based mission using their creation.  The authors provide lots of background support, with printable worksheets and troubleshooting tips.

#### Activities:

This page contains a short explanation and Java simulation of the physics behind rainbows. It explores the reflection and refraction effects of light inside a water droplet as well as polarization.  A discussion forum regarding this material is also provided.

This simulation illustrates the spectrum of hydrogen, from wavelengths of 2500 nm to 50 nm.  An energy-level diagram tool is used to create a spectrum that matches the experimental spectrum.  Energy levels and transitions can be indicated by the user.  A zoom window is also available to observe details of the spectrum.

Over the past 100 years, there has been a revolution in our ability to understand light and its various forms of radiation. This image collection, produced especially for Teachers' Domain, is a fascinating glimpse of stars, the Milky Way, and the crab nebula, photographed using four different telescopes.  Students can compare how these objects look in visible light, infrared, x-ray, and radio imaging.

This beautifully-presented NASA resource introduces students to the wonder of electromagnetic waves and their behaviors. Each segment of the spectrum is described & illustrated, and accompanied by a video clip. Don't miss the newly available EMS book, "Tour of the Electromagnetic Spectrum, available for online viewing or free download.

#### References and Collections:

An award-winning set of tutorials created by an astronomer to give beginning students a brief overview of astronomy's place in the scientific endeavor.  The section linked here on electromagnetic radiation is a well-sequenced resource that helps the student see that light can behave as both a wave and a particle.

### Visible Light and Color (7)

#### Lesson Plans:

For students who have explored the basics of color mixing, this is an excellent unit to continue their investigation into the subject.  This comprehensive module (same authors as the module above) takes students on a hands-on journey of the origin of colors in solids, liquids, and gases.  They will explore the color of fireworks, why the sky is blue, how glowsticks and fireflies produce phosphorescent light, and how LED's work.

#### Activities:

How do the primary colors of light combine to produce the vast array of colors we perceive?  In this simple, yet elegant simulation, students control three monochromatic lights of varied intensity to produce multiple colors.  They can also add filters and see what colors pass through to the eyes.  The PhET team created a companion assessment/worksheet to go with this simulation.  Find it directly below.

A high school teacher created this worksheet/assessment specifically to guide students in using the PhET simulation "Color Vision" (see above).  It provides step-by-step directions in using the simulation to explore the effects of mixing the primary colors of light.  A second activity helps students "see" light as a photon.  Allow two class periods with computers and internet access.

Understanding the RGB color model helps students understand how the mixing is done to produce the colors we see on electronic displays.  In this Java applet, students play around with simulated light sources to mix the three additive colors of light (red, green, and blue).  **NOTE:  Scaffolding is recommended, as there is no text explanation with the applet.  We suggest this tutorial for extra support:

The colors red, green, and blue are classically considered the primary colors of light because they are fundamental to human vision. All other colors of the visible light spectrum can be produced by adding different combinations of these three colors. This Java simulation lets students move and overlay three circles colored red, green, and blue.  Combine any two and produce the complementary colors of light (cyan, magenta, and yellow).  Combine all three and the result is white light.  We suggest introducing this simulation alongside the one directly below on subtractive (complementary) colors.

The complementary colors (cyan, yellow, and magenta) are also commonly referred to as the primary subtractive colors because each can be formed by subtracting one of the primary additives (red, green, and blue) from white light. This tutorial explores how the three primary subtractive colors interact with each other, both in pairs or all together.  Interestingly, when all three are mixed, the result is black (the absence of light). We recommend introducing this tutorial after the simulation directly above on primary additive colors.

#### Student Tutorials:

To fully understand color perception, students need to shift gears from the traditional color wheel model they learned in grade school. This is a fun, high-quality tutorial that explains why the RGB primary colors of light (red, green, blue) are different from the primary colors of pigment and paint. It's because the photoreceptors in our eyes respond to wavelengths in certain regions: red, green, and blue. These colors then combine to form the complementary colors of light: cyan, magenta, and yellow. Your students will enjoy the four Java simulations that accompany the tutorial.

### The Eye (1)

#### Student Tutorials:

This five-part tutorial on the human eye is part of the highly-regarded Physics Classroom web site.  Students work at their own pace to gain understanding of the complex physical and neural mechanisms that interact to produce human vision.