question_answer 51)

  An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. (a) The length of the telescope tube is 20-02 m. (b) The magnification is 1000. (c) The image formed is inverted. (d) An objective of a larger aperture will increase the brightness and reduce chromatic aberration of the image.

Answer:

  (a,b,c) Here,  = 20 m and = 2 cm = 0-02 m. In normal adjustment, length of telescope tube Magnification . The image formed is inverted (w.r.t. the object). Choices (a), (b) and (c) are correct