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The focal length of a slide projecter's converging lens is 10 cm. If a 35 mm slide is positioned 10.2 cm from the lens, how far away must the screen be placed to create a clear image?
PLEASEEEE!
The focal length of a slide projecter's converging lens is 10 cm. If a 35 mm slide is positioned 10.2 cm from the lens, how far away must the screen be placed to create a clear image?
PLEASEEEE!
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The lens equation is 1/So + 1/Si = 1/f
where f = focal length, So = distance that the object is from the lens and Si = distance of the image from the lens. (See http://en.wikipedia.org/wiki/Optics for a detailed explanation and a diagram that will help you inderstand it better).
Solving the lens equation for Si:
1/Si = 1/f - 1/So = (So-f)/f*So
Si = f*So/(So-f)
Si = 10*10.2/(10.2 - 10) = 510cm
where f = focal length, So = distance that the object is from the lens and Si = distance of the image from the lens. (See http://en.wikipedia.org/wiki/Optics for a detailed explanation and a diagram that will help you inderstand it better).
Solving the lens equation for Si:
1/Si = 1/f - 1/So = (So-f)/f*So
Si = f*So/(So-f)
Si = 10*10.2/(10.2 - 10) = 510cm
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s' = s*f/(s - f) = 10.2/(10.2 - 10) = 510 cm from the lens.