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The lengths of the tube of an astronom...

The lengths of the tube of an astronomical telescope is 44 cm and its angular magnification is 10 . What is the focal length of its objective ?

Text Solution

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Magnification ,
`m=(f_o)/(f_e) or, f_e =(f_o)/m`
Length of the tube,
`L=f_(o)+f_e=f_(o)+(f_o)/m=f_o(1+1/m)=f_(o)((m+1)/m)`
`f_(o)=L(m)/(m+1)=44xx(10)/(10+1)=40 cm `
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