(a) A giant refracting telescope at an observatory has an objective lens of focal length 15m. If an eyepiece of focal length 1.0cm is used, what is the angular magnification of the telescope? (b) If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is `3.48 xx 10^(6)m`, and the radius of lunar orbit is `3.8xx10^(8)m`.
Text Solution
Verified by Experts
Angular magnification, `M = ( f_(0))/( f_(e))` `= (1500 cm)/( 1cm) ` `= 1500` `("Diameter of image of moon (d)")/("Focal length of objective"(f_(0)))=("Diameter of th emoon")/("Radius of Lunar orbit") ` `d = 1500 xx ( 3.42 xx 10^(6))/( 3.80 xx 10^(6))` 13.5 cm
Topper's Solved these Questions
RAY OPTICS AND OPTICAL INSTRUMENTS
OSWAAL PUBLICATION|Exercise TOPIC-3(LONG ANSWER TYPE QUESTIONS)|5 Videos
A small telescope has an objective lens of focal length 144cm and an eyepiece of focal length 6.0cm. What is the magnifying power of the telescope? What is the separation between the objective and the eyepiece?
A small telescope has an objective lens of focal length 140cm and an eyepiece of focal length 5.0cm. What is the magnifying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e., when the final image is at infinity)? (b) the final image is formed at the least distance of distinct vision (25cm)?
(a) Define magnifying power of a telescope. (b) Write its expression. A small telescope has an objective lens of focal length 150 cm and an eye piece of focal length 5 cm. If this telescope is used to view a 100m high tower 3 x 10^(5) cm away , find the height of the final image when it is formed 25 cam away from the eye piece.
OSWAAL PUBLICATION-RAY OPTICS AND OPTICAL INSTRUMENTS-TOPIC-3(Numerical Problems)
