Physics Help Forum Light - Scale Drawing :(

 Light and Optics Light and Optics Physics Help Forum

 Dec 27th 2009, 09:29 PM #1 Junior Member   Join Date: Dec 2009 Posts: 29 Light - Scale Drawing :( Question - A converging lens is used to project an image of a slide onto a screen 1000mm from the lens, which has a focal length of 200mm. The image is a square with side 250mm. By means of a scale drawing, determine a) the distance of the slide from the lens, and b) the size of the slide. I am stucked at this question... Wishing for a kind soul to show me the scale drawing which includes steps in drawing it Thanks in advance and sorry for the trouble.. Last edited by Punch; Dec 27th 2009 at 10:12 PM.
 Dec 27th 2009, 10:02 PM #2 Senior Member   Join Date: Sep 2009 Location: india Posts: 409 a)250 mm ? b) i thought the size of the image is already given. what do u think? ...............sorry. pleaseignore this. i did not see that scale drawing is required. Last edited by r.samanta; Dec 27th 2009 at 10:04 PM. Reason: wrong post
Dec 27th 2009, 10:13 PM   #3
Junior Member

Join Date: Dec 2009
Posts: 29
 Originally Posted by r.samanta a)250 mm ? b) i thought the size of the image is already given. what do u think? ...............sorry. pleaseignore this. i did not see that scale drawing is required.
Thanks, I realize that the question is, "the size of the SLIDE".
However, still unable to solve

 Dec 27th 2009, 10:33 PM #4 Senior Member   Join Date: Sep 2009 Location: india Posts: 409 a)1/1000-1/(-u)=1/200 gives u=250 mm b)m=v/u=I/O gives 1000/250=I/O=250/O gives O=62.5 mm.
Dec 28th 2009, 12:31 AM   #5
Junior Member

Join Date: Dec 2009
Posts: 29
 Originally Posted by r.samanta a)1/1000-1/(-u)=1/200 gives u=250 mm b)m=v/u=I/O gives 1000/250=I/O=250/O gives O=62.5 mm.
lol guess i haven't been to your level yet, can u draw a scale drawing and show me how to derive the answer?sorry

 Dec 28th 2009, 05:53 AM #6 Senior Member   Join Date: Sep 2009 Location: india Posts: 409 i am sorry but i really do not draw good in computers. i am way behind u on this. however, what derivation are u asking? i used lens formula 1/v-1/u=1/f and magnification=v/u =image size/object size,with sign conventions. these must be derived in all standard textbooks?
Dec 28th 2009, 07:01 PM   #7
Junior Member

Join Date: Dec 2009
Posts: 29
 Originally Posted by r.samanta i am sorry but i really do not draw good in computers. i am way behind u on this. however, what derivation are u asking? i used lens formula 1/v-1/u=1/f and magnification=v/u =image size/object size,with sign conventions. these must be derived in all standard textbooks?
well I haven't heard or learnt anything about lens formula and magnification formula yet.

regarding the scale drawing, perhaps u can draw it out on a rough paper and take a photo of it then upload it onto the photobucket.com and paste the link here.. it's okay if it isn't possible.. lol

 Dec 28th 2009, 07:29 PM #8 Junior Member   Join Date: Dec 2009 Posts: 29 I figured how to draw already, thanks.

 Tags drawing, light, scale

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post freeflight Advanced Mechanics 1 Apr 23rd 2013 09:59 AM Ray3Ray3 Electricity and Magnetism 2 Apr 4th 2011 12:47 AM reiward Thermodynamics and Fluid Mechanics 1 Dec 8th 2010 05:04 AM Riyafa Kinematics and Dynamics 1 Sep 17th 2009 04:06 AM pramod Kinematics and Dynamics 1 Jan 23rd 2009 08:24 PM