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JDK1.0.2 simulations (1996-2001) => Optics => Topic started by: Spike on April 01, 2012, 11:33:03 am

Title: Focal length
Post by: Spike on April 01, 2012, 11:33:03 am
A astronomical telescope is used to project a real image of the moon on the screen 25 cm from the eyepiece, which has a focal length of 5 cm. How far must the eyepiece be moved from its normal position. Can anyone help me how to work this one out :)

Title: Re: Focal length
Post by: Fu-Kwun Hwang on April 01, 2012, 03:53:38 pm
It is a telescope, so the moon can be treated as an object located at infinite.
So the image is form at the focus point.

You might be able to work out the rest! :-) :D