CBSE Class 12 · 2020 · Geometrical OpticsMultiple Choice

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Larger aperture of the objective lens in an astronomical telescope:
  1. (A)Increases the resolving power of the telescope✓ Correct
  2. (B)Decreases the brightness of the image
  3. (C)Increases the size of the image
  4. (D)Decreases the length of the telescope

Answer: (A)

Solution

The resolving power of a telescope is , where is the aperture of the objective. A larger therefore \emph{increases the resolving power} (it also makes the image brighter, but the standard CBSE key is the resolving-power statement).

CBSE Class 12 Board · 2020 · Single correct option

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