In telescopes we use eye-piece which has focal length
Correct answer: B. Very small
- A. Very large
- B. Very small
- C. Variable
- D. Moderate
Explanation
The correct answer is Very small. Telescopes use eye-pieces with very small focal lengths to maximize magnification, allowing observers to see distant objects more clearly. Option A is incorrect because a large focal length results in lower magnification, not suitable for telescopes. Option C is misleading since while some telescopes may offer variability, the primary function relies on small focal lengths. Option D is incorrect because a moderate focal length does not provide the high magnification needed for effective telescopic observation.
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About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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