EASY
Earn 100

State the condition under which a large magnification can be archived in an astronomical telescope.

Important Questions on Eye and Optical Instruments

EASY
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.
MEDIUM

Draw a labelled ray diagram of an image formed by a refracting telescope with final image formed at infinity Derive an expression for its magnifying power with the final image at infinity.

MEDIUM
Derive an expression for the magnifying power of an astronomical telescope in normal adjustment.
MEDIUM

The figure shows the image formation of an object in simple microscope.

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Derive an equation for magnifying power of the simple microscope.

EASY
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:
MEDIUM
The magnifying power of objective lens of compound microscope is 06 and eye lens is 05. Find the net magnifying of compound microscope.
MEDIUM
A small telescope has an objective lens of focal length 144 cm and an eyepiece of focal length 6.0 cm. What is the magnifying power of the telescope?
EASY
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

An astronomical telescope has an objective lens of focal length 20 m and an eyepiece of focal length 1 cm. Find the angular magnification of the telescope.

MEDIUM

Draw the ray diagram of an astronomical telescope when the final image is formed at infinity. Write the expression for the resolving power of the telescope.

EASY

A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5 cm. What is the magnifying power of the telescope for viewing distant objects when the telescope is in normal adjustment.

HARD
Remote sensing satellites move in an orbit that is at an average height of about 500 km 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 cm, then the terrestrial area that can be observed from the satellite is close to:
EASY

A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5 cm. What is the magnifying power of the telescope for viewing distant objects when the final image is formed at the least distance of distinct vision.

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EASY
What is the effect on the magnifying power of a telescope if the aperture of its objective lens is increased?
HARD
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:
MEDIUM
The magnifying power of a telescope with tube length 60cm is 5. What is the focal length of its eye piece?
MEDIUM
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
A pair of stars of actual separation one minute of arc is observed with an astronomical telescope of magnifying power 100. What will be the separation of the image of the pair in degree.
EASY
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
MEDIUM

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 :