EASY

Earn 100

Draw a ray diagram of reflecting type telescope and hence given the advantage of reflecting type telescope.

Important Questions on Ray Optics

EASY

Physics>Optics>Ray Optics>Optical Instruments: 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

Physics>Optics>Ray Optics>Optical Instruments: 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

Physics>Optics>Ray Optics>Optical Instruments: Telescope

The ratio of resolving power of telescope, when lights of wavelengths

5000 \overset{\circ}{A}

and

4000 \overset{\circ}{A}

are used, is _____

EASY

Physics>Optics>Ray Optics>Optical Instruments: 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

MEDIUM

Physics>Optics>Ray Optics>Optical Instruments: Telescope

Why do prefer an objective of large aperture in a telescope?

MEDIUM

Physics>Optics>Ray Optics>Optical Instruments: 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

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

Draw a neat labelled ray diagram of a reflecting telescope of any type.

HARD

Physics>Optics>Ray Optics>Optical Instruments: Telescope

Remote sensing satellites move in an orbit that is at an average height of about

500 k m

from the surface of the earth. The camera onboard one such satellite has a screen of area

A

on which the images captured by it are formed. If the focal length of the camera lens is

50 c m

, then the terrestrial area that can be observed from the satellite is close to:

MEDIUM

Physics>Optics>Ray Optics>Optical Instruments: Telescope

What is Presbyopia? Describe the construction and working of reflecting telescope. Draw necessary ray diagram.

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

Discuss the difference between a refracting telescope and reflecting telescope by giving three points.

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

There are four lenses

L_{1}, L_{2}, L_{3}

and

L_{4}

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

MEDIUM

Physics>Optics>Ray Optics>Optical Instruments: Telescope

The magnifying power of a telescope with tube length

60 c m

5 .

What is the focal length of its eye piece?

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

If the focal length of objective lens of an astronomical telescope is

20 cm

and the length of it is

25 cm

, the`magnification of the telescope for normal adjustment is.

EASY

Physics>Optics>Ray Optics>Optical Instruments: 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:

MEDIUM

Physics>Optics>Ray Optics>Optical Instruments: 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 :

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:

EASY

Physics>Optics>Ray Optics>Optical Instruments: Telescope

For the astronomical telescope, the focal length of objective lens is