Download ANSWERS Refraction a..

Science 8
Name: _Answer Key__
Quiz Review Refraction and Reflection
Answer in short, complete sentences!
Getting in Light’s Way (Page 274-275)
1. Give three point definitions for the words below:
transparent
All or most light passes
through (transmits)
Clear
See-through
Examples:
Air, clear glass
(windows)
Plastic wrap,
Some crystals,
clear water
translucent
Lets some light through
Cloudy
blurry
opaque
It doesn’t let any light
through
Not clear
Examples:
Frosted glass
Clouds
Finger nails
Lake (muddy) water
Examples:
Bricks
Wood
Metal
Stone
2. What happens to light energy that is absorbed by a surface?
Some of the energy is converted to thermal energy. (It turns into heat.)
3. What surface colours will absorb the most light?
Black (or very dark colours) will absorb the most light.
4. What surface sheen (shininess) will absorb the most light?
A dull (not shiny) surface will absorb the most light.
5. What surface texture will absorb the most light?
A rough texture will absorb the most light.
Describing Images Page 276
6. Why is your eye an optical device?
It is an optical device because it creates an image (on the retina).
7. What is a real image? It is an image that can be placed on a screen.
8. What is a virtual image?
It is an image that only be seen by looking through an optical device. (Binoculars, most
mirrors and eyeglasses cannot produce an image on a screen.)
9. Complete the table to show how the letters SALT to help you remember the four
characteristics of images.
Characteristic
Possible Descriptions
S
size
Smaller, larger, or same size
attitude
Upright or inverted
location
Nearer, farther or same distance (from
the optical device)
type
Real or virtual
A
L
T
10. If describe the characteristics of size, attitude and type for the image below.
image
Size: larger (than object)
Attitude: upright
Type: real
object
Class notes on Refraction
11. Does light slow down or speed up in a dense medium?
Light will slow down in a dense medium.
12. When light slows down it bends (closer) toward the normal line. (toward or away?)
13. When light speeds up it bends _away _ from the normal line. (toward or away?)
14. Complete the following ray diagrams by showing estimated changes to the
refracted ray (Toward or away from the normal line, by a lot or a little?) Use a ruler!
Air
Water
Diamond
Air
normal line
normal line
Refracting Light in Lenses P. 290 (plus hands on: Exploring Lenses)
15. Which lenses are thin in the middle, and which lenses are thick in the middle?
Lenses that are thin in the middle are CONCAVE and lenses that are thick in the
middle are CONVEX.
16. When you use a convex lens to look at a nearby object, is the image smaller or
larger, upright or inverted?
The image will be larger and upright. (Think: magnifying glass!)
17. When you use a convex lens to look at a far object, is the image smaller or larger,
upright or inverted?
The image will be smaller and inverted.
18. When you use a concave lens to look at a nearby object, is the image smaller or
larger, upright or inverted?
The image will be smaller and upright.
19. When you use a concave lens to look at a FAR object, is the image smaller or larger,
upright or inverted?
The image will be smaller and upright.
20. Use dashed lines to draw the path of the rays of light entering each lens
A Telescope for every Wave Page 300
21. What is the difference between a reflecting and a refracting telescope?
A reflecting telescope uses mirrors while a refracting telescope uses lenses.
22. What are two problems related to using lenses in telescopes?
Lenses are easily broken in very large telescopes, and they cause the light to
separate into colours (spectrum)
Using Curved Mirrors Page 286
23. Which type of curved mirror creates an image that is ALWAYS virtual and upright?
A convex mirror makes an image that is always virtual and upright.
24. Which type of curved mirror creates an image that is sometimes virtual and upright
and sometimes real and inverted (depending on the distance of the object)?
A concave mirror can make an image that is virtual and upright OR real and inverted
OR virtual and inverted (can be three different types!)
25. What are two practical uses of convex mirrors?
Convex mirrors can be used for security mirrors, or for the passenger side mirror on
cars , trucks, or busses.
26. What are three practical uses of concave mirrors?
Concave mirrors can be used for cosmetic mirrors, dentists mirrors, reflectors in
flashlights, telescopes, solar collectors.
27. Why do drivers have to be careful in using convex mirrors while backing up?
“Objects may be closer than they appear”!!!
28. Why are curved mirrors so helpful as solar collectors?
They can focus a lot of light into a small area to generate heat or energy.