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Homework Help: Convex mirror question

  1. Jul 25, 2016 #1
    1. The problem statement, all variables and given/known data

    A convex spherical mirror with a focal length of magnitude 25 cm has a 4.0-cm tall flower placed 100 cm in front of it. What is the height of the image of the flower?

    a.20 cm
    b. 1.6 cm
    c .0.80 cm
    d. 4.0 cm
    e. 8.0 cm

    2. Relevant equations



    3. The attempt at a solution

    Using mirror equation I calculated di=33.3cm
    Using Magnification equation I calculated hi=1.33cm

    I thought this would be a simple problem, I don't see my mistake. Do any of you? Thanks in advance.
  2. jcsd
  3. Jul 25, 2016 #2


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    Please, show the steps in your calculation...
  4. Jul 25, 2016 #3
    you have used the correct equations, but you forget about the focal length of convex mirror is virtual, hence you should substitutes f = -25 cm, and you should get di = -20 cm , hence, hi = 0.80 cm
  5. Jul 25, 2016 #4


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    Hello yihloong, :welcome:

    Please note that in PF we don't provide the answers: we help the posters learn and understand by pointing at mistakes and by asking relevant questions. Directly giving an answer often robs the poster from a valuable learning experience
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