Aartha is viewing a distant mountain with a telescope that has a 120−cm−focal length objective lens and an eyepiece with a 2.0 cm focal length. she sees a bird that's 5.2m distant and wants to observe it. To do so, she has to refocus the telescope. 

 By how far must she move the eyepiece in order to focus on the bird?

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Focal length of the telescope f 120cm Focal leng... View the full answer