Phys 100 Astronomy Chapter 5 Review
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Phys 100 Astronomy Chapter 5 Review

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Questions and Answers

What is the wavelength of the longest wavelength light visible to the human eye?

  • 7000 nm
  • 4000 nm
  • 700 nm (correct)
  • 400 nm

    • What type of radiation has wavelengths longer than visible light?

  • X-rays
  • Gamma-rays
  • Ultraviolet light
  • Infrared radiation (correct)

    • What happens to ultraviolet radiation from a star?

  • It has a wavelength that is shorter than the x-rays emitted by the star.
  • It will penetrate Earth's atmosphere and reach the ground.
  • It has a wavelength that is longer than the visible light emitted by the star.
  • It will not penetrate Earth's atmosphere and reach the ground. (correct)

    • What is the wavelength of violet light?

    <p>400 nm</p> Signup and view all the answers

    How many nanometers are in one meter?

    <p>1×10^9</p> Signup and view all the answers

    What is the ratio of the light gathering power of a 5-m telescope to that of a 0.5-m telescope?

    <p>100</p> Signup and view all the answers

    What is the magnification of a telescope and eyepiece if the telescope objective has a focal length of 200 cm and the eyepiece has a focal length of 0.2 cm?

    <p>400 times</p> Signup and view all the answers

    Why do radio telescopes have poor resolving power?

    <p>Radio waves have long wavelengths</p> Signup and view all the answers

    What does CCD stand for in astronomy?

    <p>Charge-coupled device</p> Signup and view all the answers

    Which of the following types of electromagnetic radiation can penetrate the Earth's atmosphere to reach its surface?

    <p>Answers b and c</p> Signup and view all the answers

    What is the reason why the Hubble Space Telescope objective mirror is not affected by the Earth's atmosphere?

    <p>It is in space</p> Signup and view all the answers

    What is the main reason for building large optical telescopes on the Earth's surface?

    <p>to nullify the blurring effects of the Earth's atmosphere and thus produce higher resolution images</p> Signup and view all the answers

    Why does the Spitzer Space Telescope orbit far from Earth?

    <p>to avoid the Earth's thermal emission of infra-red radiation</p> Signup and view all the answers

    What is the correct description of refraction of light?

    <p>The change in direction of a light ray as it passes to a medium of different optical density</p> Signup and view all the answers

    What is the light-gathering power of a telescope directly proportional to?

    <p>the diameter of the primary mirror or lens</p> Signup and view all the answers

    What is the main advantage of building large telescopes?

    <p>to collect as much light as possible from faint objects</p> Signup and view all the answers

    What is the main reason for putting telescopes in space?

    <p>to avoid the Earth's atmosphere</p> Signup and view all the answers

    In which type of telescope does chromatic aberration occur when different colors of light do not focus at the same point?

    <p>Refracting</p> Signup and view all the answers

    What is the main reason for combining the signals of multiple radio telescopes across a large area?

    <p>To produce higher resolution images</p> Signup and view all the answers

    What type of telescope has a mirror as its objective?

    <p>Reflecting</p> Signup and view all the answers

    Which of the following telescopes has a larger light-gathering power?

    <p>A telescope of 6 cm diameter and focal length of 100 cm</p> Signup and view all the answers

    Why is it not a good idea to position radio telescopes close together?

    <p>To avoid interference between signals from separate telescopes</p> Signup and view all the answers

    What is the characteristic of a refracting telescope?

    <p>It has a lens as its objective</p> Signup and view all the answers

    What is a common feature of new telescopes?

    <p>using chromatic aberration</p> Signup and view all the answers

    What is the ability of a telescope to resolve fine detail known as?

    <p>resolving power</p> Signup and view all the answers

    Why is infrared astronomy often done from high-flying aircraft?

    <p>because infrared radiation is absorbed low in Earth's atmosphere</p> Signup and view all the answers

    What technique uses a high-speed computer to monitor atmospheric distortion and adjust the optics of a telescope?

    <p>adaptive optics</p> Signup and view all the answers

    What is a measure of a telescope's ability to show fine detail?

    <p>resolving power</p> Signup and view all the answers

    What type of telescope is most likely to suffer from chromatic aberration and have a low light gathering power?

    <p>a small diameter refracting telescope</p> Signup and view all the answers

    Study Notes

    Visible Light

    • The longest wavelength of visible light is approximately 700 nm.
    • The shortest wavelength of visible light is approximately 400 nm.
    • Violet light has a wavelength of approximately 400 nm.

    Electromagnetic Radiation

    • Infrared radiation has a longer wavelength than visible light.
    • Ultraviolet radiation has a shorter wavelength than visible light.
    • Gamma-rays have a shorter wavelength than X-rays.
    • Radio waves have a longer wavelength than visible light.

    Telescopes

    • Astronomers build optical telescopes on top of mountains because there is less air to dim the light and the seeing is better.
    • The light-gathering power of a telescope is directly proportional to the diameter of the primary mirror or lens.
    • The resolving power of a telescope is a measure of its ability to show fine detail and depends on the diameter of the objective.
    • The magnification of a telescope is determined by the focal length of the telescope objective and the eyepiece.

    Optical Telescopes

    • Ultraviolet radiation from a star will not penetrate Earth's atmosphere and reach the ground.
    • CCD stands for Charge-Coupled Device.
    • Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations because the wavelength of radio waves is much longer than the wavelengths of visible light.

    Radio Telescopes

    • Radio telescopes have poor resolving power because radio waves have long wavelengths.
    • Radio waves can penetrate the Earth's atmosphere to reach its surface.
    • The main reason for positioning many radio telescopes across a large area and combining the signals is to produce higher resolution images.

    Space Telescopes

    • The Hubble Space Telescope objective mirror is not affected by bad seeing or chromatic aberration.
    • The Spitzer Space Telescope orbits very far from Earth because the Earth thermally emits infrared radiation, which the telescope is also constructed to observe.

    Refraction and Reflection

    • Refraction is the change in direction of a light ray as it passes to a medium of different optical density.
    • Chromatic aberration occurs in a refracting telescope when different colors of light do not focus at the same point.
    • A reflecting telescope uses a mirror as its objective, while a refracting telescope uses a lens.

    Telescope Design

    • The main reason for building large optical telescopes on the Earth's surface is to collect as much light as possible from faint objects.
    • New telescopes use segmented mirrors, thin mirrors, and active optics to control the shape of the mirror.
    • Adaptive optics is a technique that uses a high-speed computer to monitor atmospheric distortion and adjust the optics of a telescope to partially compensate for the seeing.

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    Description

    Practice your understanding of astronomy with this review quiz, covering topics such as wavelengths of light, including visible and non-visible spectra. Test your knowledge with multiple-choice questions and see how well you've mastered the material. Ideal for students studying astronomy and physics.

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