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Instrument that is used for seeing the moon, stars and planets.

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Important Questions on Wave Optics

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An object is placed at a distance u from a microscope of focal length l. The angular magnification depends on
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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
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A convex lens of focal length 12.5 cm is used as a simple microscope. When the image is formed at infinite, Magnification is _________  (Near point for the normal vision is 25 cm).
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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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If we need a magnification of 375 from a compound microscope of tube length 150mm and an objective of focal length 5mm, the focal length of the eye-piece, should be close to:
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An object is seen through a simple microscope of focal length 10 cm. Find the angular magnification produced, if the image is formed at the near point of the eye which is 20 cm away from it.
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Given below are two statements : one is labeled as Assertion A and the other is labeled as Reason R.

Assertion A: For a simple microscope, the angular size of the object equals the angular size of the image.

Reason R: Magnification is achieved as the small object can be kept much closer to the eye than 25 cm and hence it subtends a large angle. In the light of the above statements, choose the most appropriate answer from the options given below:

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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.

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The magnifying power of a telescope with tube length 60cm is 5. What is the focal length of its eye piece?
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Draw a ray diagram to sow image formation in a compound microscope. Define its magnifying power and write relation for it.
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The image formed by the objective of a compound microscope is
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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 :

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The magnifying power of a simple microscope is (when final image is formed at D=25cm from eye)
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An object viewed from a near point distance of 25 cm, using a microscopic lens with magnification 6, gives an unresolved image. A resolved image is observed at infinite distance with a total magnification double the earlier using an eyepiece along with the given lens and a tube of length 0.6 m, if the focal length of the eyepiece is equal to ____ cm.
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In a compound microscope, the intermediate image is

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An astronomical telescope has an objective lens of focal length 20 m and an eyepiece of the focal length of 1 cm. If this telescope is used to view the Moon, find the diameter of the image formed by the objective lens. Given the diameter of the Moon is 3.5×106m and the radius of the lunar orbit is 3.8×108 m.
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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.

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What is the magnifying power of a simple microscope of focal length 5 cm, if the image is formed at the distance of distinct vision?
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It the focal length of objective lens is increased then magnifying power of:
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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: