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Wave Optics — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsWave Optics3 Marks
Question
How does the resolving power of a compound microscope get affected on:
  1. Decreasing the diameter of its objective?
  2. Increasing the focal length of its objective?
✓

Answer

Resolving limit of microscope $=\frac{\lambda}{2\text{n}\sin\theta} $
Resolving power $\alpha\frac{1}{\text{Resolving limit}}$
i.e., Resolving power $=\frac{2\text{n}\sin\theta}{\lambda}$
  1. When diameter of objective lens decreases, θ and hence sinθ decreases; so the resolving power decreases.
  2. The focal length of objective lens has no effect on resolving power of microscope.

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