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How many lenses are in a Galileo's telescope?

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Important Questions on Observing Space : Telescopes

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Science>Physics>Observing Space : Telescopes>Telescope
In normal adjustment, for a refracting telescope, the distance between objective and eye piece is 30 cm. The focal length of the objective, when the angular magnification of the telescope is 2, will be:
HARD
Science>Physics>Observing Space : Telescopes>Telescope
A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance:
EASY
Science>Physics>Observing Space : Telescopes>Telescope
The ratio of resolving power of telescope, when lights of wavelengths 5000 A∘ and 4000 A∘ are used, is _____
MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope
A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in a normal setting, the angle formed by the image of the tower is θ, then θ is close to
MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope
Why do prefer an objective of large aperture in a telescope?
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Science>Physics>Observing Space : Telescopes>Telescope
In an astronomical telescope in normal adjustment a straight black line of the length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is l . The magnification of the telescope is:
EASY
Science>Physics>Observing Space : Telescopes>Telescope
Draw a neat labelled ray diagram of a reflecting telescope of any type.
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Science>Physics>Observing Space : Telescopes>Telescope
For the astronomical telescope, the focal length of objective lens is f0 and the eye piece lens is fe. Then the tube length of the telescope is _______.
MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope
What is Presbyopia? Describe the construction and working of reflecting telescope. Draw necessary ray diagram.
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Science>Physics>Observing Space : Telescopes>Telescope
Discuss the difference between a refracting telescope and reflecting telescope by giving three points.
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Science>Physics>Observing Space : Telescopes>Telescope

The focal lengths of objective lens and eye lens of a Galilean Telescope are respectively 30 cm and 3.0 cm. Telescope produces virtual, erect image of an object situated far away from it at least distance of distinct vision from the eye lens. In this condition the Magnifying Power of the Galilean Telescope should be :

MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope
The magnifying power of a telescope with tube length 60cm is 5. What is the focal length of its eye piece?
EASY
Science>Physics>Observing Space : Telescopes>Telescope
An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer, the tree appears as
EASY
Science>Physics>Observing Space : Telescopes>Telescope
By considering the first correlation complete the second correlation: 
Hubble telescope: 569 km high from earth surface:: Revolving orbit of Hubble telescope: _____. (high earth orbit/ low earth orbit)
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Science>Physics>Observing Space : Telescopes>Telescope
There are four lenses L1,L2,L3 and L4 of focal lengths, 2,4,6 and 8 cm respectively Two of these lenses form a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are
EASY
Science>Physics>Observing Space : Telescopes>Telescope
An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears:
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Science>Physics>Observing Space : Telescopes>Telescope
A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:
MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope
Explain the reflective telescope with diagram and write its advantages over refractive telescope. On what factors does its resolving power depend?
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Science>Physics>Observing Space : Telescopes>Telescope
You are given two convex lenses of focal lengths 10 cm and 60 cm. To make a telescope, which of the two lenses will you use as object lens and which one as eye lens?
MEDIUM
Science>Physics>Observing Space : Telescopes>Telescope

In an astronomical telescope of refracting type: