Astronomical telescope refraction problem, an easy one

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SUMMARY

The forum discussion addresses the design of an astronomical telescope with an angular magnification of +5 and a total length of 16 cm. The calculations yield a focal length of the ocular lens (f_ocular) as -4 cm and the focal length of the objective lens (f_objective) as 20 cm. The user initially expresses confusion regarding the requirement for two convergent lenses in an astronomical telescope, but the consensus confirms that the provided solution is valid.

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alpyurtsever
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Homework Statement



1.a) Design an astronomical telescope with an angular magnification of +5 (pay attention to + sign !) and
length of 16 cm, i.e. compute fobjective and focular).

Homework Equations



M=-(f_objective/f_ocular)
L=f_ocular+f_objective

The Attempt at a Solution



f_objective=16-f_ocular

M=-(16-f_ocular)/f_ocular

f_ocular = -4 cm
f_objective= 20 cm

I have found like that, but it says that it is an astronomical telescope in the question, where am I doing wrong. Astronomical telescope must consist of 2 convergent lenses, isn't it?
 
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alpyurtsever said:
Astronomical telescope must consist of 2 convergent lenses, isn't it?
No, not necessarily. Your solution looks good :smile:
 

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