Question
Mon June 13, 2011 By: Amrut Bhokardankar

AN ASYRONOMICAL TELESCOPE CONSISTS OF TWO THIN LENSES 36 CM APART AND HAS NORMAL MAGNIFYING POWER 8.CALCULATE FOCAL LENGTH OF LENSES.

Expert Reply
Mon June 13, 2011
Distance between the objective lens and the eyepiece of astronomical telescope = fo +  fe;
 
where fo = focal length of objective lens and fe = focal length of eye lens
Magnifying power, m = fo/fe;
 
36 = fo +  fe;
 
m = 8 = fo/fe;
 
36 = 8 fe + fe = 9 fe;
 
fe = 4 cm
 
and fo = 32 cm 
Tue February 07, 2017

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