Science 8 Name: ______
Quiz Review Vision, Refraction and Reflection
1. Write the names for the parts of the eye next to the correct letter in the table.
a / Corneab / Iris
c / Pupil
d / Lens
e / Ciliary muscle
f / Retina
g / Optic nerve
2. Write the names for the parts of the eye next to the correct definition in the table.
Pupil / “hole” in the iris where light entersRetina / area where image forms and is made into a nerve signal
lens / helps focus light onto the retina(CHANGES SHAPE)
Optic nerve / carries nerve signals to the brain
Ciliary muscle / controls the thickness of the lens (to focus)
Cornea / outer layer that helps focus light onto the retina (TRANSPARENT)
Iris / makes the pupil larger or smaller (where your eye colour is located
3. Answer each question in complete sentences.
a. How do your iris and pupil control the amount of light entering the eye?
The iris opens the pupil to allow more light or contracts to let in less light
b. Why does your pupil appear black?
Most of the light that enters your eye is absorbed
c. Where does refraction occur in the eye?
It occurs in BOTH the cornea and the lens
d. How do your ciliary muscles and the lens help you focus on near and far objects?
The ciliary muscle stretches the lens to make it thinner so you can focus far away
e. What are the two special types of cells in your retina that detect light?
RODS and CONES
f. How are the two types of cells different? (What does each do?)
The rods detect the difference between bright and dim light to form most of the image (light a black&white photo).
There are 3 types of cones detect colour and only work if the light is bright.
Describing Images Page 276
1. Why is your eye an optical device?
It forms an image
2. What is a real image?
A real image can be placed on a screen
3. What is a virtual image?
A virtual image can only be seen by looking through an optical device – it can’t be placed on a screen
4. Complete the table to show how the letters SALT to help you remember the four characteristics of images.
Characteristic / Possible DescriptionsS / SIZE / Larger or smaller than the object
A / ATTITUDE / Upright or inverted
L / LOCATION / Distance from the device (behind or in front if considering mirrors)
T / TYPE / Real or virtual
5. If describe the characteristics of size, attitude and type for the image below.
Class notes on Refraction
6. Does light slow down or speed up in a dense medium? It SLOWS down
7. When light slows down it bends ___toward______the normal line. (toward or away?)
8. When light speeds up it bends ____away______from the normal line. (toward or away?)
9. 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)
10. Which lenses are thin in the middle, and which lenses are thick in the middle?
Concave lenses are thin in the middle, convex lenses are thick in the middle.
11. When you use a convex lens to look at a nearby object, is the image smaller or larger, upright or inverted? (Magnifying glass) nearby objects are larger and upright
12. When you use a convex lens to look at a far object, is the image smaller or larger, upright or inverted? (Magnifying glass) far objects are smaller and inverted
13. When you use a concave lens to look at a nearby object, is the image smaller or larger, upright or inverted? With concave lenses, images are ALWAYS smaller and UPRIGHT(and virtual)
14. When you use a concave lens to look at a far away object, is the image smaller or larger, upright or inverted? With concave lenses, images are ALWAYS smaller and UPRIGHT (and virtual)
15. Which lens can produce a real image? ONLY convex lenses
16. Use dashed lines to draw the path of the rays of light entering each lens
A Telescope for every Wave Page 300
17. What is the difference between a reflecting and a refracting telescope?
Refracting telescopes only use lenses, but reflecting telescopes use a lens and a mirror.
18. What are two problems related to using lenses in telescopes? You can’t use very large lenses or they may break around the edges and refraction causes the starlight to spread out into the spectral colours.
Getting in Light’s Way (Page 274-275)
19. What happens to light energy that is absorbed by a surface? It gets turned into heat
20. What surface colours will absorb the most light? Black absorbs the most
21. What surface sheen (shininess) will absorb the most light? A dull surface absorbs the most
22. What surface texture will absorb the most light? A rough surface absorbs the most
Class notes and Using Curved Mirrors Page 286
23. What is the difference between specular and diffuse reflection?
Specular reflection requires a smooth shiny surface and creates a clear image.
Diffuse reflection occurs when a dull surface reflects light but scatters it so a clear image isn’t formed
24. What are the two laws of reflection?
1st: The angle of incidence is equal to the angle of reflection
2nd: The angle of incidence, the angle of reflection and the normal line all occur in a PLANE
25. Draw a diagram (use a pencil, protractor and ruler) showing the first law of reflection.
26. Which type of curved mirror creates an image that is ALWAYS virtual and upright?
A convex mirror always creates an images that is smaller and upright (it also appears wider)
27. 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 creates different images depending on the distance from the object.
28. What are two practical uses of convex mirrors?A convex mirror can be used for security in a store or for a passenger side mirror on a car.
29. What are three practical uses of concave mirrors?A concave mirror can be used for a make-up mirror, a telescope reflector or a dentist’s mirror, solar collector.
30. Why do drivers have to be careful in using convex mirrors while backing up?The convex mirror makes objects appear far away, so you might hit it by mistake!
31. (Think) Why are concave mirrors so helpful as solar collectors?Concave mirrors focus the light to a point, so you can heat something quickly.