HW-24Solutions-03-28-08

HW-24Solutions-03-28-08 - Lehigh University HW-24 Solutions...

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Lehigh University Physics 21, Spring 2008 April 2, 2008 HW-24 Solutions 24-1. (HRW 34-43) You produce an image of the Sun on a screen, using a thin lens whose focal length is 20.0 cm. What is the diameter of the image? (See Appendix C for needed data on the Sun.) Solution: 43. Let the diameter of the Sun be d s and that of the image be d i . Then, Eq. 34-5 leads to ( )( )( ) 28 3 11 2 0 . 01 0 m 2 6 . 9 61 0m | | 1.86 10 m 1.50 10 m 1.86mm. is s s if dm d d d pp ×× ⎛⎞ == = = × ⎜⎟ × ⎝⎠ = 24-2. (HRW 34-47) An illuminated slide is held 44 cm from a screen. How far from the slide must a lens of focal length 11 cm be placed (between the slide and the screen) to form an image of the slide's picture on the screen? Solution: 47. Using Eq. 34-9 and noting that p + i = d = 44 cm, we obtain p 2 dp + df = 0. Therefore, pd d d f =±− = ± = 1 2 4 22 44 4 44 22 2 () ( ( cm 1 2 cm) cm)(11 cm) cm. 2 24-3. (HRW 34-91) Someone with a near point P n of 25 cm views a thimble through a simple magnifying lens of focal length 10 cm by placing the lens near his eye. What is the angular magnification of the thimble if it is positioned so that its image appears at (a) P n and (b) infinity? Solution: 91. (a) Without the magnifier, θ = h / P n (see Fig. 34-19). With the magnifier, letting i = – |i| = – P n , we obtain 11 11111 pfifi fP n =− =+=+ .
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This note was uploaded on 04/13/2008 for the course PHYSIC 2 taught by Professor Kim during the Spring '08 term at Lehigh University .

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HW-24Solutions-03-28-08 - Lehigh University HW-24 Solutions...

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