1bt i cldn't get 2nd step.......
Q1) A 35 mm slide with a 24 mm*36 mm picture is projected on a screen placed 12 m from the slide.The image of the slide picture on the screen measures 1.0 m *1.5 m.Determine the location of the projection lens, and its focal length.
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19 Answers
62Honey as I said to you even I am not very much convinced with this one...
And may be I am wrong altogether.. sorry for confusing you ..
62i mean there is a lens.. and then we keep a slide in between.
the image is formed in front
thus the slide(object) is in between the lens and the image..
there are other kinds of projectors so it all depends..
62i think there is a mistake in my explanatino above..
The object is in between the lens and the screen..
so things change a bit.. but the essence remains the same :)
62oh ..
that is because
u is -ve
v is mu
also the lens is in between the screen and the object
so u+v=distance between screen and object = 12 meters (given)!
62that is from the lens formula...
1/v+1/u=1/f
where m is magnification11
62honey sorry i did not understand the set up of the question :(
what does a "35mm" stand for when we already kow that the dimansion of the picture is 24x36?!!!
62so honey this is kind of obvious .. because
magnification is image height/ object height
so magnification is know
that is also equal ratio of v:u
so v=mu
now the next step is kind of obvious..
1Linear Magnification=1000/24=125/3
-[u+(125/3)u]=12
i.e. u=-9/32 m , v=375/32 m
Using 1/v-1/u=1/f
f=27.5 cm
The projection lens should be 28.1 cm from the slide and have focal length=27.5 cm
1ys.......nd after tht wtever they hd done i cldn't understand even a word
62first we can say that the lens will be convex because a real image is being formed...
We also know the magnification.
1it is the dimension of the slide nd i don't think it hv any significance in the sol.
nd i myself hvn't understood the ques so well thtz y i posted it here