Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 6, Problem 23E
Radio astronomy involves wavelengths much longer than those of visible light, and many orbiting observatories have probed the universe for
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Radio astronomy involves wavelengths much longer than those of visible light, and many orbiting observatories have probed the universe for radiation of very short wavelengths. What sorts
of objects and physical conditions would you expect to be associated with emission of radiation at very long and very short wavelengths? (Select all that apply.)
very long wavelengths
cold
cold gas
cosmic background radiation
nuclear reactions
++
Opulsars
solar corona
very high-energy processes
very short wavelengths
cold gas
cosmic background radiation
nuclear reactions
pulsars
solar corona
very high-energy processes
Voyager 2.
When the Voyager 2 spacecraft was approaching towards its Neptune encounter in
1989, it was 4.5 × 10° km away from the earth. Its radio transmitter, with which it
communicated with us (and we communicated with it), broadcast with a mere 22 Watt
of power at the S-band (2.1 GHz). (Your home wi-fi router emits around 2 Watt at 2.4
GHz wi-fi band). Assuming the Voyager transmitter broadcast equally in all directions,
(a) What signal intensity was received on the earth?
(b) What electric and magnetic field amplitudes were detected?
(c) How many 2.1 GHz photons were arriving per second on a radio-receiver antenna
with a circular cross-section of diameter 34 meters?
Two counter-propagating plane waves
(a) Let E(z, t) = E0 cos(kz – wt)â + E, cos(kz + wt)x. Write E(z, t) in simpler form
and find the associated magnetic field.
(b) For the fields in part (a), find the instantaneous and time-averaged electric and
magnetic field energy densities.
(c) Let E(z, t) = E, cos(kz – wt)x + E,…
Infrared radiation from the center of our galaxy with a wavelength of
about 2 μm (2 × 10-6 m) comes mainly from cool stars. Use this
wavelength as Amax and find the temperature of the stars.
Chapter 6 Solutions
Astronomy
Ch. 6 - What are the three basic components of a modern...Ch. 6 - Name the two spectral windows through which...Ch. 6 - List the largest-aperture single telescope...Ch. 6 - When astronomers discuss the apertures of their...Ch. 6 - The Hooker telescope at Palomar Observatory has a...Ch. 6 - What is meant by “reflecting” and “refracting”...Ch. 6 - Why are the largest visible-light telescopes in...Ch. 6 - Compare the eye, photographic film, and CCDs as...Ch. 6 - What is a charge-coupled device (CCD), and how is...Ch. 6 - Why is it difficult to observe at infrared...
Ch. 6 - Radio and radar observations are often made with...Ch. 6 - Look back at Figure 6.18 of Cygnus A and read its...Ch. 6 - Why do astronomers place telescopes in Earth’s...Ch. 6 - What was the problem with the Hubble Space...Ch. 6 - Describe the techniques radio astronomers use to...Ch. 6 - What kind of visible-light and infrared telescopes...Ch. 6 - Describe one visible-light or infrared telescope...Ch. 6 - What happens to the image produced by a lens if...Ch. 6 - What would be the properties of an ideal...Ch. 6 - Many decades ago, the astronomers on the staff of...Ch. 6 - The largest observatory complex in the world is on...Ch. 6 - Suppose you are looking for sites for a...Ch. 6 - Radio astronomy involves wavelengths much longer...Ch. 6 - The dean of a university located near the ocean...Ch. 6 - What is the area, in square meters, of a 10-m...Ch. 6 - Approximately 9000 stars are visible to the naked...Ch. 6 - Theoretically (that is, if seeing were not an...Ch. 6 - In broad daylight, the size of your pupil is...Ch. 6 - How much more light can be gathered by a telescope...Ch. 6 - How much more light can the Keck telescope (with...Ch. 6 - People are often bothered when they discover that...Ch. 6 - Telescopes can now be operated remotely from a...Ch. 6 - The HST cost about $1.7 billion for construction...Ch. 6 - How much more light can the James Webb Space...Ch. 6 - The Palomar telescope’s 5-m mirror weighs 14.5...
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