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Light travels much faster than sound. For example:

Thunder and lightning start at the same time, but we will see the lightning first. Light travels much faster than sound. For example:. Light travels VERY FAST – about 300,000 kilometers per second or 186,000 miles per second.

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Light travels much faster than sound. For example:

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  1. Thunder and lightning start at the same time, but we will see the lightning first. • Light travels much faster than sound. For example:

  2. Light travels VERY FAST – about 300,000 kilometers per second or 186,000 miles per second. At this speed light could travel the equivalent of 8 times around the world in one second!

  3. Reflection, refraction and absorption of light • In this Powerpoint presentation: • Properties of light • Colors • Reflection - Mirrors • Refraction – Lenses • Absorption

  4. We see things because they reflect light into our eyes! This is literally the only way we get to see things! ALL objects we see either create light or reflect light!! Homework

  5. Light travels in waves • Light can be either absorbed, reflected refracted, or diffracted

  6. Properties of Light summary • Light travels in straight lines and is a form of energy • Light travels much faster (a million times faster!) than sound • We see things because they reflect light into our eyes • Shadows are formed when light is blocked by an object • Visible light is only a small part of the electromagnetic spectrum; the other parts are invisible to the human eye but not necessarily the eyes of other animals.

  7. Review Properties of Light • Light is made up of photons that are packets of energy. • The energy of a photon is related to its wavelength. • Indigo light has the highest energy • because it has the higher frequencies and shortest wavelength • Red light has the lowest energy • because it has a lower frequency and longer wavelength

  8. Part 2 - Reflection

  9. Reflection • The throwing back by a body or surface of light, heat, or sound without absorbing it. • Two types of reflection: regular and diffuse

  10. Regular vs. Diffuse Reflection • Smooth, shiny surfaces have a regular reflection: Rough, dull surfaces have a diffuse reflection. Diffuse reflection is when light is scattered in different directions

  11. Refraction • Refraction is when waves speed up or slow down due to travelling in a different medium • A medium is something that light waves will travel through • Light rays are slowed down by the water • Causes the ruler to look bent at the surface • The mediums in this example are water and air

  12. Refraction • Bending of light due to a change in speed. Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

  13. Light hitting straight on is not bent Light hitting at an angle is bent

  14. ReviewofRefraction Light rays slow down when they enter a new medium Refraction can cause light rays to change their direction All transparent materials have their own “index of refraction” Light is refracted when it passes through lenses and this creates images

  15. LIGHT & USES: Diffraction • Diffraction – Bending of waves around the edge of a barrier. New waves are formed from the original. • Breaks images into bands of light & dark and colors.

  16. END

  17. Color • Part 3 - Color In this section of the Powerpoint you will learn about color and how we can mix colors to create other colors. We will also learn how light helps us to see various colors around us.

  18. Color • White light is not a single color; it is made up of a mixture of the seven colors of the rainbow. We can demonstrate this by splitting white light with a prism: This is how rainbows are formed: sunlight is “split up” by raindrops.

  19. The colors of the rainbow: • Red • Orange • Yellow • Green • Blue • Indigo • Violet Just remember ROY G. BIV

  20. Adding colors of light • White light can be split up to make separate colors. These colors can be added together again. • The primary colors of light are red, blue and green: Adding blue and red makes magenta (purple) Adding blue and green makes cyan (light blue) Adding all three makes white again Adding red and green makes yellow

  21. Homework Seeing color • The color an object appears depends on the colors of light it reflects. For example, a red book only reflects red light: White light Only red light is reflected

  22. Electromagnetic Radiation • Light is a form of energy calledElectromagnetic Radiation -Electromagnetic Radiation comes from the sun and other sources • Travels at the speed of light • Is mostly invisible • Carries energy • Is VERY important to society and is something YOU can’t be without for many reasons

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