Which of the following describes how a refracting telescope works? A. It uses two convex lenses to gather and focus light from distant objects B. It uses only mirrors to collect and focus light from distant objects C. It uses both mirrors and lenses to collect and focus light from distant objects

Which of the following describes how a refracting telescope works? A. It uses two convex lenses to gather and focus light from distant objects B. It uses only mirrors to collect and focus light from distant objects C. It uses both mirrors and lenses to collect and focus light from distant objects

Glencoe Physics: Principles and Problems, Student Edition

1st Edition

ISBN:9780078807213

Author:Paul W. Zitzewitz

Publisher:Paul W. Zitzewitz

Chapter17: Reflections And Mirrors

Section: Chapter Questions

Problem 96A

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People are often bothered when they discover that reflecting telescopes have a second mirror in the middle to bring the light out to an accessible focus where big instruments can be mounted. “Don’t you lose light?” people ask. Well, yes, you do, but there is no better alternative. You can estimate how much light is lost by such an arrangement. The primary mirror (the one at the bottom in Figure 6.6) of the Gemini North telescope is 8 m in diameter. The secondary mirror at the top is about 1 m in diameter. Use the formula for the area of a circle to estimate what fraction of the light is blocked by the secondary mirror. Figure 6.6 Focus Arrangements for Reflecting Telescopes. Reflecting telescopes have different options for where the light is brought to a focus. With prime focus, light is detected where it comes to a focus after reflecting from the primary mirror. With Newtonian focus, light is reflected by a small secondary mirror off to one side, where it can be detected (see also Figure 6.5). Most large professional telescopes have a Cassegrain focus in which light is reflected by the secondary mirror down through a hole in the primary mirror to an observing station below the telescope.
Large telescopes are usually reflecting rather than refracting. List some reasons for this choice.
Some telephoto cameras use a mirror rather than a ens. What radius of curvature mirror is needed to replace a 800 mm-focal length telephoto lens?
The X-ray image in Figure UN 5-5 shows the remains of an exploded star. Explain why images recorded by telescopes in space are often displayed in representational (“false”) color rather than in the “colors” (wavelengths) received by the telescope.
Geometric optics describes the interaction of light with macroscopic objects. Why, then, is it correct to use geometric optics to analyze a microscope’s image?
What is the purpose of adaptive optics? A. to improve the angular resolution of telescopes in space B. to eliminate the distorting effects of atmospheric turbulence for telescopes on the ground C. to increase the collecting area of telescopes on the ground D. to increase the magnification of telescopes on the ground E. to allow several small telescopes to work together like a single larger telescope
Define magnifying power of a telescope. Write its expression.A small telescope has an objective lens of focal length 150cm and an eye piece of focal length 5cm. If this telescope is used to view a 100m high tower 3km away, find the height of the final image when it is formed 25cm away from the eye piece.
Outline the invention of a telescope. Describe the working of a telescope.
Theory One significant telescope property is magnification (Mag). Magnification makes a small object appear larger. If Mag = 30X, the image is 30 times the size of the object. Related to Magnification is Field of View (FOV). FOV measures the fraction of the sky that can be viewed by the instrument. Generally, the higher the Mag, the lower the FOV. Light Gathering Power (LGP) is a measure of the light collection efficiency of the telescope. The higher the LGP, the brighter the image. LGP varies with the area (or diameter squared) of the aperture. Resolution (Res) measures the ability of the telescope to bring out fine detail. Res varies with aperture diameter. Also, Res is better for higher frequency (blue) light than for lower frequency (red light). Notice in Figure 9-1 for the Refractor that Objective focal length (fobj) and eyepiece focal length (feye) are labeled. The lens separation in this type of Refractor is feye + fobj. The magnification is fobj / feye Questions 1. A…
Theory One significant telescope property is magnification (Mag). Magnification makes a small object appear larger. If Mag = 30X, the image is 30 times the size of the object. Related to Magnification is Field of View (FOV). FOV measures the fraction of the sky that can be viewed by the instrument. Generally, the higher the Mag, the lower the FOV. Light Gathering Power (LGP) is a measure of the light collection efficiency of the telescope. The higher the LGP, the brighter the image. LGP varies with the area (or diameter squared) of the aperture. Resolution (Res) measures the ability of the telescope to bring out fine detail. Res varies with aperture diameter. Also, Res is better for higher frequency (blue) light than for lower frequency (red light). Notice in Figure 9-1 for the Refractor that Objective focal length (fobj) and eyepiece focal length (feye) are labeled. The lens separation in this type of Refractor is feye + fobj. The magnification is fobj / feye. Questions. (3.…
Telescopes do more than just magnify images. In fact, if all they did was magnify images Galileo would have never seen the moons of Jupiter. What other important thing does the telescope do? a)The telescope is better at tracking movement than the naked eye is. b)The telescope is able to take disorderly rays and collimate them. c)The telescope is able to discern more colors than the naked eye can. d)The telescope is able to gather more light than the naked eye can. Kepler's design allowed him to achieve better image quality and higher magnifications than Galileo's. However, his design has a significant drawback. What is it? a) Kepler's telescope has rays intersecting each other, which creates the possibility that they will interfere with each other. b) Kepler's telescope is less able to collimate chaotic incoming light. c) Kepler's telescope collects less light. d) Kepler's image is inverted, while Galileo's is upright.
The sun is 150,000,000 kmkm from earth; its diameter is 1,400,000 kmkm. For a science project on solar power, a student uses a 24-cmcm-diameter converging mirror with a focal length of 51 cmcm to focus sunlight onto an object. This casts an image of the sun on the object. For the most intense heat, the image of the sun should be in focus. What is the intensity of sunlight in the projected image? Assume that all of the light captured by the mirror is focused into the image. Express your answer with the appropriate units.