Problems
Problems

 1 Two waves have the same speed. Wave A has four times the frequency of wave B. How does the wavelength of wave A compare with that of wave B? 2 A wave has a frequency of 4 Hz and a wavelength of 6 m. What is the speed of the wave? 3 What is the wavelength of a wave that has a speed of 30 m/s and a frequency of 0.5 Hz? 4 A wave has a wavelength of 30 m. What would be the wavelength of the wave if its frequency were doubled but its speed remained constant? 5 What is the frequency of electromagnetic radiation that has a wavelength of 0.4 m? In what part of the spectrum does this radiation occur? 6 What is the wavelength of electromagnetic radiation that has a frequency of 3 x 1016 Hz? In what part of the spectrum does this radiation occur? 7 Saturn is ten times farther from the Sun than is the Earth. How does the flux of solar energy at Saturn compare with that at the Earth? 8 How close to the Sun would a spacecraft have to go to reach the distance at which the flux of solar energy is 20 times as large as the solar energy flux at the Earth? 9 Radio waves from a star are observed at a wavelength of 20.02 cm. If the star and the Earth were motionless with respect to each other, the radio waves would have a wavelength of 20 cm. Are the star and the Earth moving toward or away from each other. How fast are they moving toward or away from each other? 10 Suppose atoms at rest emit visible light with a wavelength of 500 nm. At what wavelength would the light from the atoms be observed if the atoms were moving toward the Earth at a speed of 20,000 km/s? 11 Photon A has twice the frequency of photon B. How do the energies of the two photons compare? 12 The wavelength of an electromagnetic wave is 3 m, and its frequency is 108 Hz. What is the index of refraction of the material through which the electromagnetic wave is passing? 13 How does the light-gathering power of a 300-m diameter radio telescope compare to that of a 50-m diameter radio telescope? 14 How much larger than a 1-m telescope would another telescope have to be in order to have 1000 times the light-gathering power? 15 Two mirrors have the same diameter. One of them has a focal ratio of f/5 and the other f/10. How do the focal lengths of the two mirrors compare? 16 A 4-m optical telescope operates at a wavelength of 5 x 10-7 m. How large would an infrared telescope operating at a wavelength of 10-4 m have to be to have the same resolution as the optical telescope? 17 What is the magnification of a telescope that has an objective with twice the focal length of its eyepiece? 18 About how large would an optical telescope need to be to achieve the angular resolution of the VLBA?

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