Grade 7/8 Science Study Guide and Sample Questions

Chapter 5 and 6 Test Date: Friday, April 27, 2012

Key Terms

Chapter 5

Rectilinear propagation Reflection Refraction

Dispersion Transparent Translucent

Opaque Ray Diagram Incident ray

Reflected ray Normal Angle of incidence

Angle of reflection Specular reflection Diffuse reflection

Plane mirror Concave mirror Convex mirror

Law of reflection Object Image

Real image Virtual image Object size

Image size Object distance Image distance

Upright Inverted Principal axis

Vertex Focal point Focal length

Diverging Converging

Chapter 6 (refraction)

Refraction Medium Bent stick effect

Angle of incidence Angle of refraction Incident ray

Refracted ray Lens Convex lens

Concave lens Converge Diverge

Sample Questions

1. When you put your hand in front of the Smartboard light your hand appears as a shadow on the board. Which property of visible light allows this to happen and why? Rectilinear propagation; beause light travels in a straight line and cannot bend around our hand!

2. Identify 2 types of reflection and provide 1 example of each. Specular (glossy paint or pictures) and diffuse (matte paints or pictures)

3. Which property of visible light allows you to see the colors of a rainbow? Dispersion – disperses white light into visible colors

4. What do we mean when we say “light travels through a vacuum”? light does not need a medium such as air or water to travel. That is how we see light from stars!

5. Using an example for each, explain how light travels through transparent, translucent and opaque materials. Transparent is see through like glass or air; translucent you cannot see through, may see shadow, such as frosted or stained glass; opaque cannot see through such as wood

6. In the following diagram, fill in the:

a) normal b) angle of incidence c) angle of reflection d) incident ray

e) reflected ray

7. What are the symbols for:

a) angle of incidence? i

b) angle of reflection? r

8. Identify the plane mirror, the concave mirror and the convex mirror.

9. Where would you use a:

Plane mirror: bathroom mirror

Concave mirror: inside of a metal spoon

Convex mirror: safety mirror on bus

10. If an angle of incidence is 47 o then what is the angle of reflection? What Law allows us to know this answer? Law of reflection says angle of incidence = angle of reflection so both are going to be 47 o

11. a) Which of the following is a real image? How do you know?

b) What do we call the image that is not real? Why? Other is a virtual image because object and image are on opposite sides of the mirror

12. SPOT

Fill in what each letter in SPOT represents.

S = size (image bigger or smaller than object?)

P = position (image closer or further from mirror than object?)

O = Orientation (image upright or inverted?)

T = Type (real or virtual?)

13. What are the SPOT characteristics for each of the following diagrams? REMEMBER: you don’t have to memorize the charts, just what SPOT stands for. You can fill in the information by looking at the diagrams!!

a)

S = Image is the same size as object.

P = Image is the same distance away from mirror.

O = Image is upright

T = image is virtual

b) concave mirror; object between mirror and F

S = image is bigger than object

P = image is further from mirror than object

O = image is upright

T = Image is virtual

c) concave mirror; object between F and 2F

S = Image is bigger than object

P = Image is further away from mirror than object

O = Image is inverted

T = Image is real

d) concave mirror; object beyond 2F

S = Image is smaller than object

P = Image is closer to mirror than object

O = Image is inverted

T = image is real

e) convex mirror

S = Image is smaller than object

P = Image is closer to mirror than object

O = Image is upright

T = Image is virtual

14. Based on the following diagram, what would the:

a) image distance be? 4 cm (same in plane mirrors)

b) image height be? 1 cm (same in plane mirrors)

15. What is the orientation of the image in the following diagram?

The image is inverted

16. Describe the position of the image in the following diagram.

The image is further from the mirror than the object

17. Describe the image size in the following diagram.

The image is smaller than the object.

18. What type of image is represented in the following diagram?

The image is real.

19. a) What does the 54o represent in the diagram below? Angle of incidence

b) How big is the angle of reflection? Same as angle of incidence, 54o

20. Which letter represents each of the following based on the diagram:

a) i = B b) Incident ray = A c) Angle of reflection = C d) r = C

e) Angle of incidence = B f) Reflected ray = D

22. Draw each of the following ray diagrams and write the SPOT characteristics for each.

Word List

Rectilinear propagation Dispersion Transparent

Opaque Translucent Refraction

Specular reflection Diffuse reflection Law of reflection

Fill in the blank:

1. Angle of incidence = Angle of reflection = Law of reflection

2. A surface in which light cannot pass through such as doors = opaque

3. Light travels in a straight line which helps make shadows = rectilinear propagation

4. Glossy photos is an example of this reflection = specular reflection

5. Reflection on a rough surface = diffuse reflection

6. A surface where you cannot see completely through, like frosted glass = translucent

7. Bending of light waves as it goes from one medium to another = refraction

8. Surface in which you can see completely through, like glass = transparent

Word List

Put the correct word next to the picture.

Law of Reflection Dispersion Real image Virtual image

Concave mirror Convex mirror Plane mirror

Dispersion Law of reflection

Real image virtual image

Concave Plane Convex

Fill in the picture

Vertex (V) Focal point (F) Principal Axis

Does this picture show convergence or divergence? Convergence

Fill in the picture

Vertex (V) Focal point (F) Principal Axis

Does this picture show convergence or divergence? Divergence

Fill in the blank

Word List

Object Object size Image Image size Focal length

Object distance Image distance Upright Inverted

Questions are based on you looking in a mirror….

1. You look in a mirror. Your physical being is the object

2. Your appearance or reflection in the mirror is the image

3. You are 3 feet tall. This is the object size

4. In a mirror, you appear taller. This is the image size

5. In a mirror you appear upside down. You are inverted

6. In a second mirror, you are right side up. You are upright

7. You are standing 2 feet from the mirror. This is the object distance

8. In the mirror, you appear to be 6 feet from the mirror. This is the image distance

9. The distance from a lens to the focal point is the focal length

Chapter 6 practice questions1. What happens to light as it passes from one medium to another (for example, when it passes from air into water)? It will bend.

2. Why are fish never exactly where we see them when we look down into the water? Our brain does not recognize that light rays bend or refract when they travel from one medium to another so the actual position of the fish is different from what we think!

3. Water is denser than air. What do we expect to happen to the speed of light rays as they travel from the air to the water? The speed of light will slow down because water is denser

4. When light travels from air to water, will the ray bend toward or away from the normal? Why? The ray will bend toward the normal because it is slowing down due to the greater density of water.

5. Fill in the diagram with:

a. Incident ray

b. Refracted ray

c. Angle of incidence

d. Angle of refraction

e. i

f. R

6. Draw a convex lens and a concave lens. Which causes rays to converge? Which causes rays to diverge? The lenses are below in question 7. Convex lens causes rays to converge. Concave lens causes rays to diverge.

7. Explain what is happening in both diagrams:

First diagram is a convex lens that shows rays converging (coming together) through the focal point.

Second diagram is a concave lens that shows rays diverging (spreading out) once they hit the focal point.

8. Where do we use concave lenses? Eye glasses to fix near sightedness

9. Where do we use convex lenses? Eye glasses to fix far sightedness and in magnifying glasses

10. If your eye refracts too much light are you near sighted or far sighted? What kind of lens do you need to fix your eye sight? You are near sighted and will have to use concave lenses

11. If your eye does not refract enough light are you near sighted or far sighted? What kind of lens would you need to fix your eye sight? You are far sighted and will have to use convex lenses