Title: 1. How is the index of refraction calculated? How is light refracted as it speeds up? How is light refracted as it slows down?
11. How is the index of refraction calculated?
How is light refracted as it speeds up? How is
light refracted as it slows down?
- Index of refraction speed of light in a vacuum
divided by speed of light in the substance - c in a vacuum
- n -------------------------------
- c in the substance
2- When light speeds up it bends away from the
normal. - When light slows down it bends toward the normal.
32. Why do you see wet spots on the road on a
hot day?
- If the air close to the ground is warmer than the
air at higher altitudes, light from the sky is
refracted upward into the observers eyes. The
blue sky appears to be on the ground and looks
like water.
43. Explain why total internal reflection occurs.
Why are prisms used as optical reflectors? Why
are diamonds so bright?
5- As light moves into a medium in which it moves
faster, it bends away from the normal. As the
angle of incidence increases, the angle of
refraction reaches 90 degrees before the angle of
incidence does.
6- At this angle of incidence, no light is
transmitted, 100 of the light is reflected. This
is total internal reflection.
7- Prisms are used as reflectors because total
internal reflection is 100. No mirrored surface
is as efficient.
8- Diamonds are bright because the critical angle
for total internal reflection in diamond is so
small that most of the light that enters the
diamond is reflected back out. The critical angle
is small for diamond because the speed of light
in diamond is so much slower than it is in air.
94. Explain how a prism disperses light.
- Different colors of light are refracted different
amounts. A prism refracts light twice
in the same direction. Each bend splits the
colors up a little more, producing a spectrum.
105. Why do stars twinkle?
- The atmosphere distorts the light from stars
because of differences in the density of air.
This distortion is seen as twinkling.
116. Why does the atmosphere make our days 4
minutes longer?
- The atmosphere refracts sunlight toward the
surface of the earth. This allows the sun to be
seen after it has passed below the horizon and
before it moves above the horizon. This adds
about 4 minutes to each day.
127. A 3 cm object is placed 10 cm in front of a
convex lens with a focal length of 5 cm. Draw a
ray diagram and calculate the location,
magnification , and size of the image formed.
What is the type and orientation of the image?
13- First draw a line parallel to the principle axis
which refracts through the focal point.
14- Then draw a line through the focal point which
refracts parallel. Where they cross is the image.
15- This image is real and inverted (case 3). We use
the equations to find the actual distance and
size of the image.
16- 1 1 1
- ------ ------ ------
- f do di
- 1 1 1
- ------ ------ ------
- 10 di
- di 10 cm
17 hi di -------
------- ho do
- hi 10 cm
- ------- -----------
- 3 cm 10 cm
- hi
3 cm, mag 1
188. A 4 cm object is placed 7 cm in front of a
concave lens with a focal length of -4 cm. Draw a
ray diagram and calculate the location,
magnification , and size of the image formed.
What is the type and orientation of the image?
19- First draw lines from each end of the object
parallel to the principle axis which refract
through the focal point.
20- First draw lines from each end of the object
parallel to the principle axis which refract
through the focal point.
21- Then draw lines from each end through the optical
center of the lens. Where they cross forms the
ends of the image.
22- This image is virtual and upright . We use the
equations to find the actual distance and size of
the image.
23 1 1 1 ------ ------ ------
f do di
- 1 1 1
- ------ ------ ------
- -4 7 di
- di -2.54 cm
24 hi di ------- -------
ho do
- hi -2.54 cm
- ------- -----------
- 4 cm 7 cm
- hi -1.45 cm, mag -0.36
259. A 5 cm object is placed 3 cm in front of a
convex lens with a focal length of 8 cm. Draw a
ray diagram and calculate the location,
magnification, and size of the image formed.
What is the type and orientation of the image?
diagram
26- First draw a line parallel to the principle axis
which refracts through the focal point.
27- First draw a line parallel to the principle axis
which refracts through the focal point.
28- Then draw a line through the optical center of
the lens. Where they cross is the image.
29- This image is virtual and upright (case 6). We
use the equations to find the actual distance and
size of the image.
30 1 1 1------ ------ ------
f do di
- 1 1 1
- ------ ------ ------
- 3 di
- di -4.8 cm
31hi di------- -------ho do
- hi -4.8 cm
- ------- -----------
- 5 cm 3 cm
- hi 8 cm, mag -1.6
3210. In what two ways can a convex lens be used to
produce an image that is larger than the object?
3311. How does the production of images with
mirrors compare with the production of images
with lenses?
- Convex mirrors produce images like concave
lenses. - Concave mirrors produce images like convex lenses.
3412. An object is placed along the principle axis
of a thin converging lens that has a focal length
of 39 cm. If the distance from the object to the
lens is 51 cm, what is the distance from the
image to the lens?
35- First draw a line parallel to the principle axis
which refracts through the focal point.
36- First draw a line parallel to the principle axis
which refracts through the focal point.
37- Then draw a line through the optical center of
the lens. Where they cross is the image.
38- Or, you could draw a line through the other focal
point which refracts parallel. All lines cross at
the image.
39- 1 1 1
- ------ ------ ------
- f do di
- 1 1 1
- ------ ------ ------
- 39 51 di
- di 160 cm
40- hi di
- ------- -------
- ho do
- hi 160 cm
- ------- -----------
- ho 51 cm
- mag 3.1 to 3.25