The diameter of objective of a telescope is $1 \mathrm{~m}$ Its resolving limit for the light of wavelength…

The diameter of objective of a telescope is $1 \mathrm{~m}$ Its resolving limit for the light of wavelength $4538 Ã…$, will be
  1. $5.54 \times 10^{-7} \mathrm{rad}$
  2. $2.54 \times 10^{-4} \mathrm{rad}$
  3. $6.54 \times 10^{-7} \mathrm{rad}$
  4. None of these

Solution

Resolving limit $d \theta=\frac{1.22 \lambda}{a}$ $=\frac{1.22 \times 4538 \times 10^{-10}}{1}$ $=5.54 \times 10^{-7} \mathrm{rad}$

Asked in: AP EAMCET 2010

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