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 Chloe_2125 #1 Posted : Saturday, June 19, 2021 5:53:22 AM Rank: NewbieGroups: Registered Joined: 4/18/2021Posts: 4Thanks: 0 timesWas thanked: 0 time(s) in 0 post(s) Hi,I am really having a hard time understanding how to approach the following question from the AAMC full length 1. I tried to use the "foil" (1/f=1/o +1/i) equation but I can't seem to get to the correct answer (B). Are you able to explain how to best solve this one?O ^__|______.__(.) 3F FIn the above figure, an object O is at a distance of three focal lengths from the center of a convex lens. What is the ratio of the height of the image to the height of the object?A.1/3B.1/2C.2/3D.3/2Thank you in advance :) Back to top User Profile
 INSTR_Katrina_128 #2 Posted : Tuesday, June 22, 2021 8:50:53 PM Rank: Advanced MemberGroups: Registered Joined: 5/18/2021Posts: 73Thanks: 0 timesWas thanked: 0 time(s) in 0 post(s) Oooh let me give it a shot!Subbing everything into the FOIL equation, we get1/f = 1/o + 1/i1/f = 1/(3f) + 1/iSolve for 1/i:1/i = 1/f - 1/(3f)Get a common denominator.1/i = 3/(3f) - 1/(3f)Add.1/i = 2/(3f)Flip both sides.i = 3/(2f) = 1.5fThey're asking about "the ratio of the height of the image to the height of the object" which is LITERALLY the definition of magnification. 😁 So...m = -i/om = -1.5f / (3f)m = -0.5The sign tells us that the image is inverted, but the question doesn't care about that.The best answer is B. Back to top User Profile
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