2_Chapter 25 HomeworkCH25 Optical Instruments

2_Chapter 25 HomeworkCH25 Optical Instruments - 338 CHAPTER...

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338 CHAPTER 25 Answers to Conceptual Questions 2. The objective lens of the microscope must form a real image just inside the focal point of the eyepiece lens. In order for this to occur, the object must be located just outside the focal point of the objective lens. Since the focal length of the objective lens is typically quite short ( ) ~1 cm , this means that the microscope can focus properly only on objects close to the end of the barrel and will be unable to focus on objects across the room. 4. For a lens to operate as a simple magnifier, the object should be located just inside the focal point of the lens. If the power of the lens is +20.0 diopters, it focal length is () 1.00 m 1.00 m 20.0 0.050 0 m 5.00 cm f == + = = P The object should be placed slightly less than 5.00 cm in front of the lens. 6. The aperture of a camera is a close approximation to the iris of the eye. The retina of the eye corresponds to the film of the camera, and a close approximation to the cornea of the
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