Answers to problems in the five parts of the work job set

Job 1. Sally and Kenny Go Wading.

Although the rock seemed to be 4 feet away, it was actually only 3.06 feet from Kenny's foot

Job 3. How a prism separates blue light from red light.

   In this part the given value of angle a can be varied. Solutions are provided for five values of this angle.

When angle "a" isangle b(red) isangle b(blue) isangle "e" between red and blue ray is
40°25.20°24.84°2.24°
45°27.90°27.50°1.92°
50°30.50°30.05°1.75°
55°32.85°32.37°1.65°
60°35.00°34.47°1.59°

Job 4. How the Human Eye Works.

   Part a. In this part the given value of Ferdinand's height can be varied. Solutions are provided for four values of this height.

When Ferdinand's height isHeight of Ferdinand's Image is
150 cm0.60 cm
160 cm0.64 cm
170 cm0.68 cm
180 cm0.72 cm
focal length of the eye-lens when Ferdinand is 10m away is 3.98 cm

   Part b. Closest distance at which student can focus. In this part the value of the student's closest object distance may vary. Solutions are provided for five values of this distance.

When student's closest distance isfocal length of student's eye lens is
15 cm3.16 cm
12 cm3.00 cm
10 cm2.86 cm
8 cm2.66 cm
5 cm2.22 cm

   Part c. Resolving Power of the human retina. In this part the value of the farthest distance that the student can resolve the ½cm letters: RZAFLPDQ may vary. Solutions are provided for three values of this distance.

Farthest distance to read RZAFLPDQsize of smallest image retina can resolve
4 meters0.0050 cm
6 meters0.0033 cm
8 meters0.0025 cm

   Part d. Size of the image of the RZAFLPDQ crater that is projected onto the un-aided human eye retina. In this part, the given value of the diameter of the crater can vary. Solutions are provided for three values of this diameter.

Given diameter of RZAFLPDQ cratersize of crater image on human eye retina
38 km0.0004 cm
57 km0.0006 cm
76 km0.0008 cm

Job 5. The Telescope.

   Part a. Since the object is almost infinitely far away, the image distance of the objective lens (the distance at which the infinitely far object is focused) is equal to the given value of the objective lens, or 76 cm.

   Part b. In this part the student is prompted to use the same value of the crater diameter that was given to the student in Job 4 Part d. Solutions are provided for the same three values of crater diameter as in 4d.

Given diameter of RZAFLPDQ craterdiameter of "first" image in telescope
38 km0.0076 cm
57 km0.0114 cm
76 km0.0152 cm

   Part c.

The focal length of the combination of eye-lens and telescope eyepiece lens combination is 1.95 cm

   Part d.

The object distance from the "first image" to the eye-eyepiece combination, for good focusing, is 3.8 cm

   Part e.

Given diameter of RZAFLPDQ craterdiameter of retinal image of the crater
38 km0.008 cm
57 km0.012 cm
76 km0.016 cm

   Part f. Yes, your retina will distinguish craters of any of the three diameters.

   Part g.

The magnification of the telescope is 20

   Part h.

The ratio of the focal length of the objective lens to the focal length of the eyepiece lens is 20

This suggests that the magnification of a telescope is equal to the ratio of the focal length of the objective lens to the focal length of the eyepiece lens. This is in fact generally true, and it can be proved.


Back to Job #1: Sally and Kenny go Wading
Back to Job #2: The famous fishing pole paradox
Back to Job #3: How a prism separates blue light from red light
Back to Job #4: The World's First Camera, or, How the Human Eye Works
Back to Job #5: The Telescope, or How the Dutch Lens Grinders Made Galileo Famous
On to the Telescope Lab: Take two lenses and make a telescope right there in the lab

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