1. Light and Sound

2. Part 1 – Properties of Light
Light travels in straight lines:
Laser

3. Light travels VERY FAST – around 300,000 kilometres per second.
At this speed it can go around the world 8 times in one second.

4. Albert Einstein

5. Light travels much faster than sound. For example:
Thunder and lightning start at the same time, but we will see the lightning first.
2) When a starting pistol is fired we see the smoke first and then hear the bang.

6. We see things because they reflect light into our eyes:
Homework

7. Shadows
Shadows are places where light is “blocked”:
Rays of light

8. Properties of Light summary
Light travels in straight lines
Light travels much faster than sound
We see things because they reflect light into our eyes
Shadows are formed when light is blocked by an object
COPY

9. Part 2 - Reflection Reflection from a mirror: Mirror Normal
Incident ray
Reflected ray
Angle of incidence
Angle of reflection
Mirror

10. LIGHT & ITS USES - Reflection
I. Reflection – Bouncing back of light waves
A. Regular reflection – mirrors smooth surfaces scatter light very little. Images are clear and exact.
B. Diffuse reflection – reflected light is scattered due to an irregular surface.
COPY

11. Regular vs. Diffuse Reflection
Smooth, shiny surfaces have a clear, regular reflection:
Rough surfaces have a diffuse reflection.
Diffuse reflection is when light is scattered in different directions
COPY

12. FOCAL POINT
Focal Point – Point where reflected or refracted rays meet and image is formed
COPY

13. Lens
Lenses have two sides, and either side can be plane, concave, or convex
A lens is a transparent object with at least one curved side that causes light to bend (or refract).
COPY

14. Concave Lenses - All images are straight and appear smaller.
- Lenses that are thicker at the edges and thinner in the center.
Diverges (spreads apart) light rays
The De-Magnifier
COPY TOP ONLY

15. Convex Lenses Thicker in the center than edges. The Magnifier
Lens that converges (brings together) light rays.
Forms real images and virtual images depending on position of the object
The Magnifier
Convex Lenses - THE MAGNIFIER

16. What if the mirror isn’t flat?
Curved mirrors
What if the mirror isn’t flat?
2) A car headlight
1) A periscope

17. View kacleaveland's map
"Have you ever approached a giant concave mirror? See your upside-down image suspended in mid-air. Walk through the image to see a new reflection, right-side-up and greatly magnified. In the background you see reflected a room full of visitors enjoying other
Taken in a place with no name (See more photos or videos here)
View kacleaveland's map
Concave Mirrors
Curves inward
May be real or virtual image
COPY

18. Convex Mirrors Curves outward Reduces images Virtual images
Use: Rear view mirrors, store security…
COPY
CAUTION! Objects are closer than they appear!

19. Part 3: Refraction of Light
Refraction – Bending of light waves due to a change in speed through an object.
Prisms – Glass that bends light. Different frequencies are bent in different amounts and light is broken out into different colors.
COPY (IN COLOR)

20. Refraction (Cont.)

21. Words – speed up, water, air, bent, medium
Refraction
Refraction is when waves ________ or slow down due to travelling in a different _________. A medium is something that waves will travel through. When a pen is placed in water it looks like this:
In this case the light rays are slowed down by the water and are _____, causing the pen to look odd. The two mediums in this example are ______ and _______.
Words – speed up, water, air, bent, medium
COPY (Exit Ticket)

23. How You See
Near Sighted – Eyeball is too long and image focuses in front of the retina
Far Sighted – Eyeball is too short so image is focused behind the retina.
© 2000 Microsoft Clip Gallery
© 2000 Microsoft Clip Gallery

24. LIGHT & USES: Lenses Concave Lenses – Vision – Eye is a convex lens.
Nearsightedness – Concave lenses expand focal lengths
Farsightedness – Convex lenses shortens the focal length.

26. 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.

27. Color of Light Transparent Objects:
Light transmitted because of no scattering
Color transmitted is color you see. All other colors are absorbed.
Translucent:
Light is scattered and transmitted some.
Opaque:
Light is either reflected or absorbed.
Color of opaque objects is color it reflects.
© 2000 Microsoft Clip Gallery

28. Color of Light Color of Objects
White light is the presence of ALL the colors of the visible spectrum.
Black objects absorb ALL the colors and no light is reflected back.
FINAL SLIDE – Color of Light
© 2000 Microsoft Clip Gallery

29. The End