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Wave Optics — Physics STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 SciencePhysicsWave Optics3 Marks
Question
Estimate the smallest angular separation of two stars which can be just resolved by the telescope having objective of diameter $25 cm$. The mean wavelength of light is $555 nm$.
✓

Answer

Data : $\lambda=555 nm 555 \times 10^9 m$
$D=25 cm =25 \times 10^2 m$
$\theta=\frac{1.22 \lambda}{D}=\frac{1.22 \times 555 \times 10^{-7}}{25 \times 10^{-2}}$
$=2.708 \times 10^6 rad$
This is the required angular separation.

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