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Ray Optics and Optical Instruments — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsRay Optics and Optical Instruments3 Marks
Question
Define the term 'resolving power' of an astronomical telescope. How does it get affected on?
  1. Increasing the aperture of the objective lens?
  2. Increasing the wavelength of the light used?
Justify your answer in each case.
✓

Answer

Resolving power (R.P) is the reciprocal of limit of angular resolution OR any other suitable definition.
  1. Increases:
Resolving power $ = \frac{\text{d}}{1.22\lambda}$

$\therefore$ R.P is directly proportional to ‘d’ (For a given $\lambda$)
  1. Decreases:
$\therefore$ R.P is inversely proportional to $'\lambda'$ (For a given d).

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