# Diameter of the objective lens of a telescope is $250\:cm$ . For light of wavelength $600\:\:nm$. coming from a distant object , the limit of resolution of the telescope is close to : Option 1) $1.5\times10^{-7}\:\:rad$ Option 2) $2.0\times10^{-7}\:\:rad$ Option 3) $3.0\times10^{-7}\:\:rad$ Option 4) $4.5\times10^{-7}\:\:rad$

$\Delta \theta =0.61\times\frac{\lambda}{r}$

$=0.61\times\frac{(600\times10^{-9})}{1.25}$

$=2.92\times10^{-7}\simeq 3\times10^{-7}\:\:rad$

Option 1)

$1.5\times10^{-7}\:\:rad$

Option 2)

$2.0\times10^{-7}\:\:rad$

Option 3)

$3.0\times10^{-7}\:\:rad$

Option 4)

$4.5\times10^{-7}\:\:rad$

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