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    hey i have this short problem:

    my answers are:

    (a)
    f = 10 cm
    i (distance to the image from the lense) = 25 cm
    and so using the thin lense equation:
    

\frac{1}{f}= \frac{1}{o} + \frac{1}{i}
    

therefore \ o = (\frac{1}{10cm} - \frac{1}{25cm})^{-1}
    

= 16.67 cm = 17 cm
    which means the object is 17 cm from the lense.

    and for part (b) my answer is:
    

\frac{image \ size}{object \ size} = \frac{-i}{o}

    Therefore  image \ size = -1.2cm

    there the image is 1.2 cm long (or tall i assume they really mean) but it is inverted and real.
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    and for part (c) i would draw something like this:
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    Yeah seems all right!
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    cool, thanks
    would you be able to help me with one too?
    http://www.thestudentroom.co.uk/show...59#post2817359

    Thanks mc_watson

    -Sarah
 
 
 
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