1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help Needed Please!

  1. Sep 14, 2004 #1
    Hey all,
    Grade 11 physics assignment due tmrw and im having some trouble. Any help would be appreciated. So here it is:

    A candle of height 4.8 cm is placed 38.6 cm in front of a converging mirror with curvature 30.2 cm. What is the height of the image?

    Heres what I have:

    1/f = 1/Di + 1/ Do so..... 1/15.1 = 1/Di + 1/38.6 so Di=2.56


    Hi/Ho = -Di/Do so............ Hi/4.8 = -2.56/38.6 so Hi=-.32

    Ho= Height of object (candle)
    Do= Distance of object
    Di= Distance of image
    Hi= Height of image
    f=focus (which i have calculated to be 15.1)

    The answer i get is -.32cm which doesn't seem right to me. Am i doing something wrong? Missing something??

    As well.... a totally unrelated question- When looking at interference patterns of water through 2 openings, if the second nodal line is formed at an angle of 50 degrees, will n=1 or n=1/2?

    Thanks for any help!!!
    Last edited: Sep 14, 2004
  2. jcsd
  3. Sep 15, 2004 #2
    Are you unsure of the sign or the magnitude of your answer? Or both?
  4. Sep 15, 2004 #3


    User Avatar
    Science Advisor
    Gold Member

    Try solving the image problem backwards.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook