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NEET PHYSICSRAY OPTICS AND OPTICAL INSTRUMENTSEasy

Question

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:

A

a large aperture contributes to the quality and visibility of the images.

B

a large area of the objective ensures better light-gathering power.

C

a large aperture provides a better resolution.

D

all of the above.

Step-by-Step Solution

  1. Light Gathering Power: The objective lens needs to collect light from distant, often faint, objects. The light-gathering power is directly proportional to the area of the objective lens (Area∝Aperture2Area \propto \text{Aperture}^2). A larger aperture ensures a brighter image, improving visibility.
  2. Resolving Power: The ability of a telescope to distinguish distinct details is called its resolving power, given by the formula RP=D1.22λRP = \frac{D}{1.22\lambda}, where DD is the aperture (diameter) of the objective. A larger aperture (DD) results in higher resolution.
  3. Image Quality: Since a large aperture improves both brightness (visibility) and resolution, it directly contributes to the overall quality of the image.
  4. Focal Length: A large focal length (fof_o) is required for high magnifying power, as magnification m=fo/fem = f_o/f_e. Thus, large focal length and large aperture are ideal characteristics.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from RAY OPTICS AND OPTICAL INSTRUMENTS. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSRAY OPTICS AND OPTICAL INSTRUMENTSlengthaperturesuitedobjectiveastronomical

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