| Never enter units in your answers. Be
sure to use the units indicated on the HW submission page.
Enter numbers without commas. 23,546 should be 23546 Always enter a * for multiplication. g(H+h) should be g*(H+h). |
| You are now obtaining input data for CID = |
|
Submitted Answers will be graded W
10/29, Th 10/30, F 10/31, and M 11/3 at 12:00 noon.
| Problem 7.1 | |||||||||||||
| What you should learn: When you do optics problems, it’s always a good idea to draw a ray sketch so you can be sure your answer has the basic characteristics you respect. The first four problems require you do a ray sketch and then describe the image. Do not consider the problem to be completed unless you have actually drawn the ray sketch. | |||||||||||||
| Problem: Do a ray
sketch for a converging (concave) mirror where the object is inside the
focal length. Determine if the image is real or virtual and enlarged or
reduced.
A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
| Hints: See the sketches in the text and Power Point slides. Note that you may have to trace emerging rays back behind the mirror to find the image. | |||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.2 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a converging (concave) mirror where the object is outside the
focal length but inside the radius of curvature. Determine if the image
is real or virtual and enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.3 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a converging (concave) mirror where the object is outside the
radius of curvature. Determine if the image is real or virtual and
enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.4 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a diverging (convex) mirror. Determine if the image is real
or virtual and enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.5 | |||||||||||||
| What you should learn: This is an application of the mirror equation, 1/f = 1/p +1/q. Be careful about signs in these problems. | |||||||||||||
| Problem: A convex
mirror is used for a side mirror on a truck. The focal length of the
mirror is f. If a car is located 25.0 m behind the mirror, what
is the distance from the mirror to the image? (Call this distance d.
This should be a positive number.) Note that in this and other problems, you are given the absolute value of f; you must determine the correct sign. |
|||||||||||||
| Constants and fixed variables:
Distance from mirror to car: D = 25.0 m |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 7.00 - 10.0 m Submit HW answers. |
|||||||||||||
| Problem 7.6 | |||||||||||||
| What you should learn: This is another application of the mirror equation. | |||||||||||||
| Problem: You place a candle in front of a converging mirror such that the size of the image is the same as the size of the candle. Find an expression for the object distance p in terms of the focal length f . | |||||||||||||
| Hints:
What do I do here? |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: Submit HW answers. |
|||||||||||||
| Problem 7.7 | |||||||||||||
| What you should learn: Ray sketches are also useful for lenses. Again, you must do the ray sketch for the next four problems to be considered complete. | |||||||||||||
| Problem: Do a ray
sketch for a converging (convex) lens where the object is inside the
focal length. Determine if the image is real or virtual and enlarged or
reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Hints: See the sketches in the text and Power Point slides. Note that you may have to trace emerging rays back behind the lens to find the image. | |||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.8 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a converging (convex) lens where the object is between the
focal length and twice the focal length. Determine if the image is real
or virtual and enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.9 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a converging (convex) lens where the object distance is
larger than twice the focal length. Determine if the image is real or
virtual and enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.10 | |||||||||||||
| What you should learn: More practice with ray sketches. | |||||||||||||
| Problem: Do a ray
sketch for a diverging (concave) lens. Determine if the image is real or
virtual and enlarged or reduced. A. Real, enlarged B. Real, reduced C. Virtual, enlarged D. Virtual, reduced E. None of the above |
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.11 | |||||||||||||
| What you should learn: This is an application of the lens law, 1/f = 1/p +1/q. Be careful about signs in these problems. | |||||||||||||
| Problem: A camera lens has a 50 mm focal length. If you take a picture of your friend who is standing a distance p in front of the camera, how far is the image from the focal point? (Enter a positive value for the distance. You may call this d.) | |||||||||||||
| Constants and fixed variables:
The magnitude of f is 50.0 mm |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
| Hints: Is f positive or negative? How do you know? | |||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: d = |f–q| = 0.500 to 0.900 mm Submit HW answers. |
|||||||||||||
| Problem 7.12 | |||||||||||||
| What you should learn: This problem makes use of the magnification: M = –q / p | |||||||||||||
| Problem: If your friend from the previous problem is wearing glasses that are 13.0 cm across, what is the size of the image of her glasses? (You may call this size w.) | |||||||||||||
| Constants and fixed variables:
The width of the glasses: wg = 13.0 cm |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 1.30 - 2.30 mm Submit HW answers. |
|||||||||||||
| Problem 7.13 | |||||||||||||
| What you should learn: In this problem you need to use the definition of magnification in conjunction with the lens equation. | |||||||||||||
| Problem: You use a convex lens with focal length f to make an image of a distant object with object distance p. Find an expression for M, the magnification of the image, in terms of f and p. | Hints: You will have two equations in two unknowns. | ||||||||||||
Results of previous submissions:
|
|||||||||||||
| Submit HW answers. | |||||||||||||
| Problem 7.14 | |||||||||||||
| What you should learn: In this problem you have to use magnification when the object distance is very large, but the object size is also very large. | |||||||||||||
| Problem: You want to burn a hole in a piece of paper by focusing the sun on it. Your lens has a focal length f. What is d, the diameter of the sun’s image on the paper? (Assume that you orient the paper so that the image of the sun is circular.) | |||||||||||||
| Constants and fixed variables:
Distance from the earth to the sun: R = 1.49x108 m Diameter of the sun rsun = 1.38x106 m |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
| Hints: The results of the previous problem should be useful. | |||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 0.900 to 2.10 mm Submit HW answers. |
|||||||||||||
| Problem 7.15 | |||||||||||||
| What you should learn: This problem is an application of the lens equation to corrective lenses. Note that you do not need to take into consideration the lens of the eye, you only need to put the image of the corrective lens in a location where the eye can focus on it. | |||||||||||||
| Problem: You wish to read the newspaper by holding the paper a distance of 30.0 cm from your eyes. However, you are farsighted and cannot focus anything closer than d. You can correct your vision by using reading glasses of what power P (in diopters)? | |||||||||||||
| Constants and fixed variables:
Reading distance: p = 30.0 cm |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
| Hints: Is the image real or virtual? Power in diopters is obtained by finding 1/f where f must be in meters. | |||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 2.30 to 2.80 diopters Submit HW answers. |
|||||||||||||
| Problem 7.16 | |||||||||||||
| What you should learn: This is one more application to corrective lenses. | |||||||||||||
| Problem: You are nearsighted and cannot clearly see anything farther than a distance d from your eyes. What power of glasses would you prescribe? | |||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
| Hints: Is the image real or virtual this time? Why? Where is the object? | |||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: –1.25 to –0.700 diopters Submit HW answers. |
|||||||||||||
| Problem 7.17 | |||||||||||||
| What you should learn: A simple magnifier works by allowing you to place the object closer to your eye than you normally could. The image of the magnifier is at a distance where your eye can focus on it. For relaxed viewing, the image distance becomes infinite. In this case, the angular magnification is given by the simple expression m = 25 cm / f | |||||||||||||
| Problem: A magnifying lens has a focal length of f. What is its (minimum) angular magnification m? (The minimum magnification corresponds to the magnification for relaxed viewing.) | |||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 2.00 - 3.20 Submit HW answers. |
|||||||||||||
| Problem 7.18 | |||||||||||||
| What you should learn: Our only problem with multiple lens systems is this telescope problem. Whether we have a reflecting or a refracting telescope, the angular magnification (the power) is given by the ratio of the focal lengths of the objective lens and the eyepiece. | |||||||||||||
| Problem: You wish to build a reflecting telescope with an angular magnification of m = 120. You have a mirror with a focal length of f. What should be the focal length of your eyepiece, fe? | |||||||||||||
| Constants and fixed variables:
Angular magnification: m = 120 |
|||||||||||||
Variables that must be changed with each
submission:
|
|||||||||||||
Results of previous submissions:
|
|||||||||||||
| Answer Range: 11.0 -20.0 mm Submit HW answers. |
|||||||||||||