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why should objective of a telescope have...

why should objective of a telescope have larger focal length ?

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To obtain larger magnifying power and better intensity of image.
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The objective of an astronomical telescope has a focal length of 80cm . The telescope is focused for normal vision of distant objects when the tube length is 1.0m .If the focal length of eye piece is f_(e) (in cm ) and magnifying power of telescope is m then the value of (f_(e))/(m) is :

The aperture and focal length of the objective of telescope are large, why?

Knowledge Check

  • The objective of terrestrial telescope has a focal length of 80 cm and its magnifying power is 20, when focal length 20 cm, the total length of such a telescope is

    A
    164 cm
    B
    124 cm
    C
    100 cm
    D
    84 cm

  • The objective of terrestrial telescope has a focal length of 80 cm and its magnifying power is 20, when adjusted for parallel rays. If the erecting lens has focal length 20 cm, the total length of such a telescope is

    A
    164 cm
    B
    124 cm
    C
    100 cm
    D
    84 cm

  • Assertion : If objective and eye lens of a mcroscope are interchanged then it can work as telsecope. Reason : The object of telescope has large focal lengths.

    A
    Assertion is True, Reason is True , Reason is a correct exaplanation for Assertion.
    B
    Assertion is True, Reason is True : Reason is not correct exaplanation for Assertion.
    C
    Assertion is True. Reason is False
    D
    Assertion is False, Reason is False.

    • Similar Questions

    Explore conceptually related problems

    What is the magnifying power of a telescope whose objective and eyepiece have focal lengths 180 cm and 3 cm, respectively ?

    Consider the following statements about a microscope and a telescope 1. Both the eyepiece and the objective of a microscope are convex lenses. 2. The focal length of the objective of a telescope is lerger than the focal length of its eyepiece. 3. The magnification of a telescope increases with the increases in focal length of its objective. 4. The magnification of a microscope increases with the increases in focal length of its objective. Which of the statements given above are correct?

    Assertion : If objective and eye lenses of a microscope are interchanged then it can work as telescope. Reason : The objective of telescope has small focal length.

    The objective of a small telescope has focal length 120 cm and diameter 5 cm. The focal length of the eye piece is 2 cm. The magnifying power of the telescope for distant object is -

    Consider the following statements. Focal length of the eyepiece of telescope is smaller as compared to the objective which has a larger focal length and aperture. For larger focal length of objective than eyepiece, magnification is more in astronomical telescopes. Which of the following statements is/are correct?

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