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Unformatted text preview: Solution for Homework 24 Curved Interfaces (Required by Not Collected) Solution to Homework Problem 24.1(Maxwell and Coulomb) Problem: Which of Maxwell’s equations is most closely related to Coulomb’s law? Select One of the Following: (aAnswer) Gauss’ Law (b) No magnetic Monopoles (c) Faraday’s Law (d) Ampere’s Law (e) Toby. Solution (a) Gauss’ law related charge to electric field, just as Coulomb’s law. Total Points for Problem: 3 Points Solution to Homework Problem 24.2(Lab Telescope) Problem: One of the lab lenses used for activity 27 has focal length 20cm . (a)Calculate the magnifying power of this lens used as a simple magnifer. (b)The shortest lens in lab has a focal length of 5cm . Calculate the magnifying power of a telescope using the 20cm lens as the objective and the 5cm lens as the eyepiece. (c)How far apart should the lenses be placed to form a telescope? Solution to Part (a) The magnifying power of the a simple lens is calculated when the image forms at infinity. The magnifying power of a simple lens is given by MP = ℓ np f = 25cm 20cm = 1 . 25 Grading Key: Part (a) 2 Points Solution to Part (b) The magnifying power of a telescope if the ratio of the focal lengths MP = f o f e = 20cm 5cm = 4 Grading Key: Part (b) 2 Points Solution to Part (c) The lenses must be placed so their focal points coincide, so the distance between lenses must be d = 20cm+5cm = 25cm . Grading Key: Part (c) 2 Points 1 Total Points for Problem: 6 Points Solution to Homework Problem 24.3(Lab Microscope) Problem: We can build a compound microscope using the two 5cm lenses from lab. We will use the standard tube length of L = 16cm . (a)Calculate the magnifying power of a 5cm lens used as a microscope objective. (b)Calculate the magnifying power of a 5cm lens used as a microscope eyepiece. (c)Calculate the total power of the microscope. (d)Approximately how far apart should the lenses be placed. Solution to Part (a) The magnifying power of the objective MP objective = parenleftbigg L f o parenrightbigg = parenleftbigg 16cm 5cm parenrightbigg = 3 . 2 Grading Key: Part (a) 2 Points Solution to Part (b) The magnifying power of the eyepiece is the magnifying power of a simple magnifier MP eyepiece = ℓ np /f e = 25cm / 5cm = 5 . Grading Key: Part (b) 2 Points Solution to Part (c) The total magnifying power is the product of the power of the two lenses, MP = 3 . 2 · 5 = 16 . Grading Key: Part (c) 2 Points Solution to Part (d) The lenses should be placed the two focal lengths plus the tube length apart d = 5cm + 16cm + 5cm = 26cm . Grading Key: Part (d) 2 Points Total Points for Problem: 8 Points Solution to Homework Problem 24.4(Intensity of Laser Beam) Problem: Club Lavella claims to be the ”Worlds largest” Beach Club. Neil says it has a 5W laser to run its light show. Assume the laser creates a 1cm radius beam....
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This note was uploaded on 04/19/2008 for the course PHYS 2074 taught by Professor Stewart during the Spring '08 term at Arkansas.
 Spring '08
 Stewart
 Physics, Work

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