describe a telescope it's uses and formulas related to it
( ray optics- class 12 )
Answers
Explanation:
The telescope is used to provide angular magnification of distant objects. The objective has a large focal length and a much larger aperture than the eyepiece because object is very far away. ... This image acts as an object for the eyepiece; it magnifies this image producing a final inverted
Telescope, device used to form magnified images of distant objects. The telescope is undoubtedly the most important investigative tool in astronomy. It provides a means of collecting and analyzing radiation from celestial objects, even those in the far reaches of the universe.
Most refracting telescopes use two main lenses. The largest lens is called the objective lens, and the smaller lens used for viewing is called the eyepiece lens.
Primary mirror (for reflecting telescopes), which carries the same role as the primary lens in a refracting telescopes. Eyepiece, which magnifies the image. Mounting, which supports the tube, enabling it to be rotated. Telescopes can be divided into two main categories: refractors and reflectors.
Telescope is used to observe objects which are very far from us. Telescopes produce magnified images of distant objects. In a simple telescope two lenses are used, objective lens and eyepiece lens. A parallel beam of light is focused by the objective lens of a telescope and then light passes through an eyepiece forming a magnified image.
It consists of two converging lenses placed coaxially. The one facing the distant object is called the objective and has a large aperture and a large focal length. The other is called the eyepiece, as the eye is placed close to it. It has a smaller aperture and a smaller focal length. The lenses are fixed in tubes. The eyepiece tube can slide within the objective tube so that the separation between the objective and the eyepiece may be changed.
When the telescope is directed towards a distant object PQ, the objective forms a real image of the object in its focal plane. If the point P is on the principal axis, the image point P is at the second focus of the objective. The rays coming from Q are focused at Q′. The eyepiece forms a magnified virtual image P′′Q′′ of P′Q′. This image is finally seen by the eye. In normal adjustment, the position is so adjusted that the final image is formed at infinity. In such a case, the first image P′Q′ is formed in the first focal plane of the eyepiece. The eye is least strained to focus this final image. The image can be brought closer by pushing the eyepiece closer to the first image. Maximum angular magnification is produced when the final image is formed at the near point.
Suppose, the objective and the eyepiece have focal lengths fo and fe respectively and the object is situated at a large distance u0 from the objective. The object PQ in figure subtends an angle α on the objective. Since the object is far away, the angle it would subtend on the eye, if there were no telescope, is also essentially α.
Asu0 is very large, the first image P′Q′ is formed in the focal plane of the objective.
