On passing thorugh a telescope a flux of light increases its intensity `eta = 4.0.10^(4)` times. Find the angular dimension of a distance object if its image formed by that telescope has an angualr dimension `Psi = 2.0^(@)`.

A thin converging lens is placed between an object and a screen whose position are fixed. There are two positions of the lens at which the sharp image of the object is formed on the screen. Find the transverse dimension of the object if at one position of the lens the image dimension equal h' = 2.0 mm and at the other, h'' = 4.5 mm .

A concave mirror of focal length 0.15 m forms an in image doubled of the linear dimension of the object. If the image is virtual then the object distance—

The dimensions of a cuboid are in the ratio 2:3:4. Its total surface area is 1872cm^(^^)2. Find its dimensions.

The diameter of the moon is 3.5 xx 10^(3) km and its distance from the earth is 3.8 xx 10^(5)km . It is seen through a telescope having focal lengths of objective and eye-piece as 4m and 10 cm respectively. Calculate (a) magnifying power of telescope (b) length of telescope tube and (c) anngular size of image of moon.

The diameter of the moon is 3.5 xx 10^(3) km and its distance from the earth is 3.8 xx 10^(5)km . It is seen through a telescope having focal lengths of objective and eye-piece as 4m and 10 cm respectively. Calculate (a) magnifying power of telescope (b) length of telescope tube and (c) anngular size of image of moon.

Two lenses L_(1) and L_(2) are used to make a telescope. The larger lens L_(1) is a convex lens with both surfaces having radius of curvature equal to 0.5 m. The smaller lens L_(2) has two surfaces with radius of curvature 4 cm. Both the lenses are made of glass having refractive index 1.5. The two lenses are mounted in a tube with separation between them equal to 1 cm less than the sum of their focal length. (a) Find the position of the image formed by such a telescope for an object at a distance of 100 m from the objective lens L_(1) . (b) What is the size of the image if object is 1 m high? Do you think that lateral magnification is a useful way to characterize a telescope? (c) Angular magnification is defined as ratio of angle subtended by the image at the eyepiece to the angle subtended by the distant object at an unaided eye. Find the angular magnification of the above mentioned telescope.

If both the object and image are at infinite distances form a refracting telescope its magnifying power will be equal to

A telescope is used to resolve two stars separated by 4.6xx10^(-6) rad. If the wavelength of light used is 5460 Å , what should be the aperture of the objective of the telescope ?