Microscopes and telescopes both consist of two converging lenses contained in a
ID: 1838086 • Letter: M
Question
Microscopes and telescopes both consist of two converging lenses contained in a tube. What is the difference in set-up of the two lenses between a microscope and a telescope? The rearview mirror on a truck warns the user that objects may be closer than they appear. What kind of mirror is being used, and why was that type selected? Why does a clear stream always appear to be shallower than it actually is? Discuss the type of aberration involved in each of the following situations. (i) The edges of the image appear reddish. (ii) The image cannot be clearly focused. A baby fish has his eyesight tested and is found to be myopic. His father wants to make a set of glasses to correct for this problem. Since fish live under water, the father fish will make the glasses out of a very thin clear plastic bag which is filled with air (n = 1.000). What type of lens does the fish need to make? What shape should the lens be? What is the wavelength of yellow light?Explanation / Answer
In refracting telescopes, there are typically two convex lenses. One lens acts as the objective lens: this lens gathers light from faraway objects and forms a real, inverted image of the object at its focal point. A second lens, called the eyepiece, is positioned such that the image formed by the objective lens is at its focal point. When an observer looks through the eyepiece with a relaxed eye, they are able to see an object of the image, formed at infinity. Microscopes are used to look at magnified images of small objects. A simple microscope (a “magnifying glass”) consists of a single convex lens. The lens is held close to the object so that the object is between the lens and its focal point. When viewed from the other side of the lens, a magnified, virtual, upright image is seen. The compound microscope is the most common type of microscope used in laboratories. With these microscopes, an objective lens is used to create an inverted, real image of the object. Using the eyepiece, the image is magnified. In this sense, its operating principles are similar to that of a refracting telescope. The rear view mirror is a convex mirror which forms a virtual and erect image of the object which is smaller in length than the object. Because the image formed is smaller in length, it appears to be farther away and hence, the warning written on it. This is because of the phenomenon of refraction of light as it crosses the medium of water(refractive index greater than that of air). As the light ray travels from water(denser medium) to air(rarer medium), the light ray bends away from the normal and the image of the bottom of the stream seems to be raised and hence, the stream appears to be shallower. a) In optics, chromatic aberration (CA, also called chromatic distortion, and spherochromatism) is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have different refractive indices for differentwavelengths of light. b) Optical Aberrations are departures of the performance of an optical system from the predictions of paraxial optics. Aberration leads to blurring of the image produced by an image-forming optical system. It occurs when light from one point of an object after transmission through the system does not converge.