Question
An astronomical telescope having an objective of focal length 100 cm is focused on the moon. Find the distance through which the eyepiece should be pulled back to focus an object situated at a distance 80 m from the objective:

None of these



easy
Solution
When the telescope is focused to moon, the objective forms the image at a distance of 100 cm from it. When the telescope is focused at an object at
As the image is shifted (100/79) cm towards the eyepiece, it should be pulled back through (100/79) cm to focus the image in normal adjustment.
SIMILAR QUESTIONS
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