Concept explainers
BIO What is 20/20 vision? Vision is often measured using the Snellen eye chart, devised by Dutch ophthalmologist Herman Snellen in 1862 (see Figure 24.29). With normal vision (20/20 vision), you can distinguish a letter that is 8.8 mm high from other letters of similar height at a distance of 6.1 m (20 ft) (the Snellen chart in the figure is smaller than normal size). If your vision is 20/40 the letters must be twice as high to be distinguishable. Alternatively, a person with 20/40 vision could distinguish letters from 20 ft that a person with 20/20 vision can distinguish at 40 ft. Someone with 20/60 vision could distinguish letters at 20 ft that someone with 20/20 vision could distinguish at 60 ft.
Does the Rayleigh criterion limit visual resolution? Assume that the eye's pupil is 5.0 mm in diameter for 500-nm light The Rayleigh criterion angular deflection for such light entering the eye's pupil is
If the Rayleigh criterion limited visual resolution, then from a distance of 6.1 m, you should be able to distinguish details in shapes of size
What is the visual acuity of a person with 20/20 vision mainly limited by?
a. The Rayleigh criterion
b. Chromatic aberration
c. Focal length of the eye lens
d. Diameter of the eye's pupil
e. The density of cones and rods
f. A combination of these factors
Want to see the full answer?
Check out a sample textbook solutionChapter 24 Solutions
College Physics
Additional Science Textbook Solutions
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Physics (5th Edition)
College Physics
Sears And Zemansky's University Physics With Modern Physics
University Physics (14th Edition)
University Physics with Modern Physics (14th Edition)
- Why is your vision so blurry when you open your eyes while swimming under water? How does a face mask enable clear vision?arrow_forwardThe normal power for distant vision is 50.0 D. A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the power of her eyes. What is the closest object she can see clearly?arrow_forwardEndoscopes are medical instruments used to examine the gastrointestinal tract and other cavities inside the body. The light required for examination is conducted from an outside source along a long, flexible bundle of optical fibers to the tip, where it exits and illuminates the internal cavity. A lens on the lip collects an image of the lighted cavity and another fiber bundle conducts the image back along the endoscope to an eyepiece for viewing (Fig. P22.52). If each fiber in the bundle has diameter d = 1.00 104 m and refractive index n = 1.40, find the smallest outside radius R permitted for a bend in the fiber if no light is to escape. Figure P22.52arrow_forward
- Endoscopes are medical instruments used to examine the gastrointestinal tract and other cavities inside the body. The light required for examination is conducted from an outside source along a long, flexible bundle of optical fibers to the tip, where it exits and illuminates the internal cavity. A lens on the lip collects an image of the lighted cavity and another fiber bundle conducts the image back along the endoscope to an eyepiece for viewing (Fig. P22.52). If each fiber in the bundle has diameter d = 1.00 104 m and refractive index n = 1.40, find the smallest outside radius R permitted for a bend in the fiber if no light is to escape. Figure P22.52arrow_forward(a) A laser vision correction reshaping the cornea of a myopic patient reduces the power of his eye by 9.00 D, with a 5.0 uncertainty in the final correction. What is the range of diopters for spectacle lenses that this person might need after LASIK procedure? (b) Was the person nearsighted or farsighted before the procedure? How do you know?arrow_forwardA certain childs near point is 10.0 cm; her far point (with eyes relaxed) is 125 cm. Each eye lens is 2.00 cm from the retina. (a) Between what limits, measured in diopters, does the power of this lenscornea combination vary? (b) Calculate the power of the eyeglass lens the child should use for relaxed distance vision. Is the lens converging or diverging?arrow_forward
- A diverging lens has a focal length of 20.0 cm. Use graph paper to construct accurate ray diagrams for object distance of (a) 40.0cm and (b) 10.0 cm. In each case, determine the location of the image from the diagram and the image magnification, and state whether the image is uptight or inverted. (c) Estimate the magnitude of uncertainty in locating the points in the graph. Are your answers and the uncertainty consistent with the algebraic answers found in Problem 33?arrow_forward(a) Use the thin-lens equation to derive an expression for q in terms of f and p. (b) Prove that for a real object and a diverging lens, the image must always be virtual. Hint: Set f = |f| and show that q must be less than zero under the given conditions. (c) For a real object and converging lens, what inequality involving p and f must hold if the image is to be real?arrow_forwardThe power for normal distant vision is 50.0 D. A severely myopic patient has a far point of 5.00 cm. By how many diopters should the power of his eye be reduced in laser vision correction to obtain normal distant vision for him?arrow_forward
- Suppose a man stands in front of a mm-or as show below. His eyes are 1.65 m above the floor and the top of his head is 0.13 m higher. Find the height above the floor of the top and bottom of the smallest minor in which he can see both the top of his head and his feet. How is this distance related to the man’s height?arrow_forward. A person looks at a statue that is 2 m tall. The image on the persons retina is inverted and 0.005 m high. What is the magnification?arrow_forwardA cataract is cloudiness in the lens of the eye. Is light dispersed or diffused by it?arrow_forward
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning