Summary

• Spherical mirrors
• Three principal rays
• Mirror equation

Today's joke





• Refraction images

• light rays
• spherical refracting surfaces
• sign conventions
• flat refracting surfaces
• interactive refraction image applet

Example #1
Example #2









• Thin lenses
• principal rays
• sign conventions
• interactive lens applet
• Lens/mirror ray diagram applet

Example #3
Example #4
Example #5
Example #6




• Practice:
  Try these additional examples
Example #7

Example #8

Example #9



• Prepare:
  Read textbook sections 16-4, 16-5, and 16-7 before the next lecture

POP5 26.25
An 8-cm thick flint glass plate (n = 1.66) is covered by 12 cm of water. How thick does it appear from above the water?
A. 1.66 cm
B. 2.41 cm
C. 4.82 cm
D. 5.34 cm
Answer













SB5 36.25
If a goldfish is 10.0 cm from the wall of a 15.0-cm-radius spherical fishbowl, how far from the wall does it appear to an outside observer?
A. 9.01 cm
B. 10.0 cm
C. 7.33 cm
D. 12.5 cm
Answer













Knight2 23.stt.06
The image of a slide on a screen is blurry because the screen is in front of the image plane. To focus the image, should you move the lens toward the slide or away from the slide?
A. toward
B. away
Answer













POP5 26.37
The nickel's image in the figure has twice the diameter of the nickel and is 3.36 cm from the lens. What is the focal length of the lens?
A. 7.24 cm
B. 6.72 cm
C. 4.82 cm
D. 3.36 cm
Answer













POP5 26.35
A single thin lens is to project the real image of a 24.0-mm-high slide so that it fills a screen that is 1.80 m high. If the slide-to-screen distance is 3.00 m, what is the focal length of the appropriate lens?
A. −75 cm
B. +3.90 cm
C. +75.0 cm
D. +296 cm
Answer













POP5 26.54
An object is positioned L = 2.00 m from a screen. A converging lens is used to make a real image of the object on the screen from two different locations that are separated by d = 89.4 cm. What is the focal length of the lens?
A. 4.47 cm
B. 25.0 cm
C. 40.0 cm
D. 80.0 cm
Answer















Walker5e 26.55
A coin is lying at the bottom of a pool of water that is 1.8 m deep. When viewed from directly above, how far below the surface of the water does the coin appear to be?
A. 0.45 m
B. 1.35 m
C. 1.80 m
D. 2.40 m
Answer















Walker5e CnEx 26-17
If a converging lens is immersed in water instead of air, does its focal length increase, decrease, or stay the same?
A. increase
B. decrease
C. stay the same
Answer















Walker5e EYU 26.6
The lenses shown below have objects that are identical in size and location relative to the lens. Is the image produced by lens 1 larger than, smaller than, or the same size as the image formed by lens 2?
A. larger than
B. smaller than
C. the same size as
Answer























 



C. 4.82 cm




















 



A. 9.01 cm




















 



B. away
There is an inverse relationship between object and image distances. In this case, in order to decrease the image distance so that it falls on the screen, we must increase the object distance. That means moving the lens away from the object (the slide).



















 



D. 3.36 cm




















 



B. +3.90 cm




















 



C. 40.0 cm























 



B. 1.35 m

Refraction makes the image of the coin appear shallower than it is by a factor of n_air/n_water = 1/1.33 = 3/4.




















 



A. increase
There is a smaller difference of index of refraction between water and glass than between air and glass. As a result, the light rays bend less at each boundary and the focal length of the lens becomes longer.




















 



A. larger than
The image produced by lens 1 will be virtual, upright, and magnified. The image produced by lens 2 will be virtual, upright, and reduced.