7_Ch 25 College Physics ProblemCH25 Optical Instruments

7_Ch 25 College - Optical Instruments 25.7 343 Since the exposure time is unchanged the intensity of the light reaching the film should be doubled

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Optical Instruments 343 25.7 Since the exposure time is unchanged, the intensity of the light reaching the film should be doubled so the energy delivered will be doubled. Using the result of Problem 6 (part a), we obtain () 22 2 1 21 2 1 -number -number 11 61 2 I ff I  ==   = , or 2 -number 61 7.8 f Thus, you should use the 8.0 f setting on the camera. 25.8 To focus on a very distant object, the original distance from the lens to the film was . To focus on an object 2.00 m away, the thin lens equation gives 1 65.0 mm qf ( )( ) 3 3 2.00 10 mm 65.0 mm 67.2 mm 2.00 65.0 mm × = −×− 2 2 2 pf q Thus, the lens should be moved qq ∆= − 2.2 mm farther from the film q = 25.9 This patient needs a lens that will form an upright, virtual image at her near point (60.0
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/09/2011 for the course PHYS 2020 taught by Professor Staff during the Fall '10 term at FIU.

Ask a homework question - tutors are online