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 Nov 1st 2009, 05:59 PM #1 Junior Member   Join Date: Sep 2009 Posts: 15 Optics - Reflection Help! An object located in front of a concave mirror with a radius of curvature of 80 cm produced an inverted image that is three times the size of the object. What is the object distance? 1/f = 1/do + 1/di hi/ho = -di/do those are the 2 formulas we are given where: f = focal point do = distance object di = distance image hi = height image ho = height of object i have no clue on where to start and what formula i should be using...
 Nov 1st 2009, 09:02 PM #2 Physics Team   Join Date: Feb 2009 Posts: 1,425 The focal length of the mirror is half its radius of curvature. Find f and just use the formulas you have shown. You have hi/ho = 3 = - di/do . Express either di or do in terms of the other , plug into the f equation and solve.
 Nov 1st 2009, 09:23 PM #3 Junior Member   Join Date: Sep 2009 Posts: 15 ok so: 3 = - di/do 3do = -di 1/f = 1/do + 1/di 1/40 = 1/do + 1/3do and then?
 Nov 1st 2009, 09:45 PM #4 Junior Member   Join Date: Sep 2009 Posts: 15 nvm i got it. i forgot how to common factor but its all good. thank you so much man! <3
Nov 2nd 2009, 07:38 PM   #5
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 Originally Posted by quick.on.my.feet ok so: 3 = - di/do 3do = -di 1/f = 1/do + 1/di 1/40 = 1/do + 1/3do and then?
An object located in front of a concave mirror with a radius of curvature of 80 cm produced an inverted image that is three times the size of the object. What is the object distance?

Nov 2nd 2009, 07:44 PM   #6
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 Originally Posted by anwaar An object located in front of a concave mirror with a radius of curvature of 80 cm produced an inverted image that is three times the size of the object. What is the object distance?
An object located in front of a concave mirror with a radius of curvature of 80 cm produced an inverted image that is three times the size of the object. What is the object distance?
Ans:-
3d0/40=3d0/d0+3d0/3d0
3d0/40=3+1
d0=160/3 = 53.3cm

Nov 2nd 2009, 07:45 PM   #7
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 Originally Posted by anwaar an object located in front of a concave mirror with a radius of curvature of 80 cm produced an inverted image that is three times the size of the object. What is the object distance? Ans:- 3d0/40=3d0/d0+3d0/3d0 3d0/40=3+1 d0=160/3 = 53.3cm
no job is too difficult

 Nov 5th 2009, 06:59 PM #8 Junior Member   Join Date: Sep 2009 Posts: 15 i said i got it lol...

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