Question

An astronomical telescope has a large aperture to
A. Reduce spherical aberration
B. Have high resolution
C. Increases span of observation
D. Have low dispersion

Answer 1

Hint: An astronomical telescope is used to see a distant object like stars, galaxies and planets. An aperture is the hole or opening of a lens from which light can pass. Here, we will understand the construction of astronomical telescopes to get the required answer.

Complete answer:
An astronomical telescope is an optical instrument that is used to see the magnified image of distant bodies like stars, planets, satellites and galaxies etc. the astronomical telescope forms an image that is always virtual, inverted and magnified. An astronomical telescope contains two convex lenses that are placed between an object and an eye. The lens that is placed near an object is known as an objective lens and the lens that is placed near the eye is known as an eyepiece.

The focal length of the objective lens is greater than the focal length of the eye piece. The objective lens and the eyepiece both are placed at the free ends of two sliding tubes and at a suitable distance from each. The aperture of the objective lens is greater than the eye piece such that it can receive more light from the distant object and form a bright image of the object. Therefore, we can say that an astronomical telescope has a large aperture to have high resolution of a distant object.

Hence, option B is the correct option.

Note:An astronomical telescope works on the principle of providing the magnified image of the distant object. When an object is placed at a large distance from the object, it will provide a virtual, inverted and magnified image. The image is formed at a least distance of distinct vision from the eye that is held close to the eye piece.