Flash Card Phys 295 - Summary Astronomy - Concepts Of The Universe PDF

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3-Ole Rømer in 1675 3-The first person to prove that light did not travel at infinite speed was 3-The flash will arrive earliest through the evacuated tube, and later through the water-filled tube. A flash of light is sent simultaneously into two parallel tubes of length 1 km—one evacuated, the other filled with water. There is a detector to sense the arrival time of the light flash at the end of each tube. What will be the relationship between arrival times of these light flashes? higher than the frequency of red light. 3-The frequency of blue light is twice the energy of each photon of the red light Suppose a light source is emitting red light at a wavelength of 700 nm and another light source is emitting ultraviolet light at a wavelength of 350 nm. Each photon of the ultraviolet light has There will be more IR photons than UV photons. In a particular beam of radiation, which is traveling in a vacuum, the amounts of energy per second at an ultraviolet wavelength of 300 nm and at an infrared wavelength of 800 nm are found to be equal. In this beam, how do the numbers of photons per second at each of these wavelengths compare? four times the magnifying power (two divided by one-half = four) An amateur astronomer is using a telescope that has a 50-cm focal length objective lens and an eyepiece of 2 cm focal length. His sister is using a telescope with an objective lens having twice the focal length and an eyepiece of half the focal length. What overall magnifying power does his sister's telescope have compared to his own? 2 cm An amateur astronomer has a telescope with an objective lens of diameter 20 cm and focal length 100 cm. What focal length of eyepiece should he choose to obtain a magnification of 50x ("50 power")? 2500 times more Many fortunate amateur astronomers have telescopes with primary mirrors 20 cm in diameter. The Keck telescopes on Hawaii have mirrors 10 m in diameter. How much more light is collected by one of the Keck telescopes compared to the amateur's telescope? making the mirror surface a parabolic shape. Spherical aberration in the primary mirror of a reflecting telescope is generally avoided by refraction of light by turbulent currents of air of differing density The so-called seeing effect on the image of an astronomical source that causes "twinkling" of the image is produced by what effect in the Earth's atmosphere? rapidly change the shape of the telescope mirror.

Fifty years ago (in the 1960s), the largest telescope on Earth was the 200-inch (5.08m) Hale telescope at Mt. Palomar in California. It was an excellent telescope, but today's large astronomical telescopes have much better angular resolution. The most important reason for this is that today's telescopes Combining the signals from two or more widely spaced telescopes that are observing the same object. What is involved in the astronomical technique of interferometry? to attain much better angular resolution than is possible with a single telescope What is the primary reason astronomers combine the signals from several radio telescopes placed at widely separated locations around the Earth? tubular-looking mirrors that utilize grazing reflection 3-X-ray telescopes in space use it absorbs all energy falling on it and emits a characteristic spectrum of radiation whose intensity as a function of wavelength depends only on its temperature. A perfect blackbody is so-called by scientists because identical if the blackbodies are at the same temperature, but not otherwise. Two physicists, one in Europe and one in North America, have each constructed an ideal blackbody in their laboratories. The two blackbodies are made from very different materials. Without conducting tests, they know that the radiation emitted by these two objects is each square meter of the star's surface each second. The energy flux, F, from a star is the amount of energy emitted by 40,000 K An astronomer measures the wavelength of peak emission of a bright star to be 73 nm. What is the temperature of the surface of this star? 81 times more Suppose the Sun had a temperature of 17,400 K (three times its present temperature) but was the same size it is now. How much more energy would the Sun emit per second? Helium Which chemical element was discovered in spectra of the Sun more than 20 years before it was found on Earth? piece of glass with thousands of evenly spaced, parallel lines cut into it. A diffraction grating, used to break light into its colors in a modern spectrograph, consists of a a cooler layer of gas overlies the deeper, hotter layers of the solar atmosphere. The presence of dark lines in the solar spectrum, the so-called Fraunhofer lines, means that

Rutherford The person who first showed that most of the mass of an atom is concentrated in a very small volume at the center of the atom was 0.05% An electron is added to a completely ionized hydrogen atom to make it electrically neutral. How much extra mass is added to the atom in this process, expressed as a fraction of the final mass? three times as massive Tritium is a radioactive form of hydrogen in which the nucleus contains one proton and two neutrons. How much more massive is this nucleus than that of ordinary hydrogen? 29 The nucleus of an atom of the copper isotope 63Cu contains 29 protons and 34 neutrons. How many electrons must be removed from a neutral 63Cu atom to completely ionize it, leaving only a nucleus? from n = 3 to n = 2 To produce the primary H-alpha (Hα) Balmer spectral line in emission, an electron must jump between which two energy levels in the hydrogen atom? If we travelled to the Sun and then back to Earth, we would have travelled 2 astronomical units overall. True The solar corona is much cooler than the Sun's surface, hence we must wait for a total solar eclipse to glimpse it with the naked eye. False All telescopes will bring the light from a star to a focus. False The primary purpose of a telescopes is to collect a large amount of light and bring it into focus. Most radio telescopes are laid out like which optical telescope design? prime focus reflector The speed of light in a vacuum is 300, 000 km/sec. The Sun's observed spectrum is a continuum with absorption lines. The amount of diffraction and thus the resolution of the scope depends on the wavelength used and the size of the main telescope objective lens or mirror.

How long does the sunspot cycle last, on average? About 11 years What is true of radio telescopes? They have poorer angular resolution than a optical telescope of the same size. What is the resolution of a telescope? Its ability to distinguish two adjacent objects close together in the sky. The angular resolution of an 8 inch diameter telescope is _________ greater than that of a 2 inch diameter telescope. 4x The temperature of the photosphere is about 5, 800K. As the Sun rotates, an individual sunspot can be tracked across its face. From eastern to western limb, this takes about two weeks. In astronomy, an interference can be used to improve the angular resolution of radio telescopes. What is the meaning of the solar constant? The amount of energy the Earth receives per unit area and unit time. Which of the following is NOT a reason to use a reflecting telescope rather than a refractor? Lenses are harder to focus than mirrors In Bohr's model of the atom, electrons only make transitions between orbitals of specific energies. What are neutrino oscillations? Neutrinos changing form. As the sun spot cycle moves from a minimum to maximum what is true about the location of the sun spots? They initially form at higher latitudes but start forming closer to the equator. What problem does adaptive optics correct? turbulence in the Earth's atmosphere that creates twinkling The solution to the solar neutrino problem was 2/3 of the neutrinos transform into a new type during the 8 minute trip to Earth. Consider this diagram. Which statement is true? The amplitude is 4 (vertical of diagram) and the wavelength is 6 (horizontal). If a wave's frequency doubles and its speed stays constant, its wavelength is halved.

Medium A blocks more of a certain wavelength of radiation than medium B. Medium A has a higher opacity. Sunspots are dark splotches on the Sun. Which statement is true? They are extremely hot, but cooler than the surrounding areas of the Sun. The two forms of electromagnetic (E-M) radiation that experience the least atmospheric opacity are light and radio waves. Electromagnetic radiation can behave both as a wave and as a particle. The design of modern X-ray telescopes depends on grazing incidence optics. Sunspots come in pairs, representing the north and south magnetic fields. Typically a granule in the photosphere is about the size of Texas, about 1,000 km across. One advantage of the Hubble Space telescope over ground based ones is that in orbit, it can operate close to its diffraction limit at visible wavelengths. In general, the spectral lines of molecules are more complex than those of atoms. Compared to a 5 inch prime focus reflector, a 5 inch Newtonian reflector will have the same light gathering power. The critical temperature to initiate the proton-proton cycle in the cores of stars is 10 million K. Which of these is emitted when an electron falls from a higher to lower orbital? a photon During a period of high solar activity, the corona is more irregular. Visible sunspots lie in the granulation in the photosphere. The observed spectral lines of a star are all shifted towards the red end of the spectrum. What does this show? The star is moving away from us.

What is the light-gathering power of an 16 inch telescope compared to a 4 inch telescope? 16× better Green light has a shorter wavelength than orange light. In a 5 inch telescope, green light will provide better angular resolution than orange light. From inside out, which is in the correct order for the structure of the Sun? core, convective zone, chromosphere, transition zone, corona The outward pressure of hot gas in the Sun is balanced by the inward gravitational pressure. The speed of light is 3.00 × 108 m/s. If 1.00 kg of mass is converted to energy, how much energy will be produced? 9.00 × 1016 J Suppose a large flare is detected optically. How long until radio interference arrives? Simultaneously Which is the net result of the proton-proton chain? 4 protons ->1 helium 4 + 2 neutrinos + gamma rays Compared to optical telescopes, radio telescopes are built large because radio waves have very long wavelengths. A jar filled with gas is placed directly in front of a second jar filled with gas. Using a spectroscope to look at one jar through the other you observe dark spectral lines. The jar closest to you contains the cooler gas. While observing the Sun, you note a large number of sunspots. What can you conclude? There are likely to be an above average number of flares and prominences. Increasing the temperature of a blackbody by a factor of 2 will increase its energy by a factor of 16...