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vorcil
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Homework Statement
A telescope objective is 12cm in diameter and has a focal length of 150cm.
Light of mean wavelength 550nm from a distant star enters the scope as a nearly collimated beam.
compute the radius of the central disk of light forming the image of the star on the focal plane of the lens
Homework Equations
[tex] \theta_{min\frac{1}{2}} = \frac{1.22*\lambda}{D} [/tex]
Radius of disk =[tex] L * \theta_{min\frac{1}{2}} [/tex]
The Attempt at a Solution
after showing the proof for those equations all I did was solve for the radius of the disk by plugging in the numbers,
[tex] \frac{1.22 * (550*(10^{-9}))}{\frac{12}{100}m}*\frac{150}{100}m [/tex]
putting into a calculator I got 8.3875*10^-6, approximately 8.39*10^-6
however the answers show 8.39*10^-4,
what am I missing?