Astro I 13 Exam II Fall 2001

   1  The electromagnetic waves named  below with the shortest wavelength are
   x x-rays
      infrared waves
      visible waves
      ultraviolet waves

   2  Telescopes with low magnification must have
      better resolution
      more light gathering power
      less image distortion
      larger objectives
   x ratio of objective to eyepiece focal lengths near one

   3  If a telescope lens were increased to four times its diameter, the image would have
      twice its previous intensity
      twice its previous size
      four times its previous focal length
   x 16 times its previous brightness
      less resolution

   4  The Sun's peak emission is yellow-white. Which of the below are hotter than the Sun?
      an orange star
   x a blue star
      a red star
      both orange and red star
      all three stars

   5  The first to accurately measure the speed of light was
      Galileo Galilei
      Isaac Newton
      Willebrord Snell
   x Olaus Romer
      James Clerk Maxwell

   6  The speed of light in a vacuum is known to
      change with the speed of the source
      depend on its frequency
   x be fixed in value
      vary with the motion of the observer
      depend on its wavelength

   7  For a given medium, light frequency depends inversely on its
   x wavelength

   8  The atmosphere of the Earth strongly absorbs
      visible and radio waves
      infrared and microwaves
      radio and gamma rays
   x ultraviolet and x-rays
      cosmic rays

   9  Absorption spectra are usually associated with
      black bodies
      white bodies
      hot gases
   x cold gases
      electrons losing energy

  10  The frequency at which a star's light intensity is maximum increases with the star's
   x surface temperature
      absorption spectra
      emission spectra

  11  The temperature of the surface of the Earth is near
      30 Kelvin
   x 300 Kelvin
      3,000 Kelvin
      30,000 Kelvin
      3 million Kelvin

  12  If a star's surface had a temperature twice our Sun's, compared to the Sun, its light intensity would be
      four times
      eight times
   x sixteen times
      thirty two times

  13  Both light and sound waves
      are vibrations of a material
      have the same speed
   x can diffract around barriers
      carry the same energy per particle
      are transverse waves

  14  The following is an ionizing radiation
      radio waves
      visible light
   x gamma rays
      infrared waves

  15  The light emitted from excited hydrogen has definite colors because
      these are the colors of the electrons
      the electron in hydrogen behaves like a planet
   x the hydrogen electron energies are quantized
      light energy is quantized
      colors correspond to frequencies

  16  If you view the spectrum of  a cold gas in space nearby to a star, you are likely to see
      emission lines without a continuous spectrum
      absorption lines in a weak continuous spectrum
      a continuous spectrum without emission lines
   x emission lines and a weak continuous spectrum
      absorption lines in a strong continuous spectrum

  17  The resolution of optical telescopes on the ground are principally limited by
      wave resolution
      light-gathering power
   x atmospheric absorption and turbulence
      earth tremors
      optical instrument aberrations

  18  When the Viking spacecraft is four times its current distance from Earth, the radio signal we detect will be
      four times weaker
   x sixteen times weaker
      two hundred and fifty six times weaker
      one thousand and twenty four times weaker
      four thousand times weaker

  19  From the spectrum of a star, we can measure
   x the star's surface temperature
      the star's mass
      the star's radius
      the star's power
      the star's brightness

  20  Chromatic aberration is caused by
   x light dispersion in lenses
      color deflection from a mirror
      distortion due to the shape of a lens
      a deviation of a mirror's focus
      absorption in the lens

  21  Spherical aberration can occur with
      lenses only
      mirrors only
   x lenses and mirrors
      parabolic dishes
      ball lightning

  22  Hertz experimentally verified the existence of
      Gamma rays
   x radio waves
      cosmic rays
      light waves

  23  Newton discovered
      light is a wave
   x prismatic colors
      light is a collection of particles
      the speed of light is constant

  24  Light can be polarized because it is
   x a transverse wave
      a longitudinal wave
      a collection of particles
      able to be magnetized
      produced at the poles

  25  The energy of a photon increases with
      light speed
   x light frequency
      light wavelength
      its mass
      its polarization

  26  Light is known to show
      only wave properties
      simultaneously both particle and wave particles
      only particle properties
      neither wave nor particle properties
   x particle or wave properties, but not both at once

  27  Light is generated and detected by
      charges at rest
   x accelerating charges
      charges moving at fixed speed
      vibrating masses
      neutral matter

  28  The law of reflection can explain
   x the action of mirrors
      lens image formation
      the dispersion of light
      the resolution of a telescope
      the diffraction of waves

  29  The absorption spectrum of hydrogen
   x is present in starlight
      is made by heating hydrogen gas
      is the same as helium
      is invisible
      was predicted by Einstein

  30  The resolution of the human eye is about
      one degree of arc
   x one minute of arc
      one second of arc
      as good as a 1 meter telescope
      half a centimeter

  31  The inner electrons in heavy elements absorb light with frequencies in the
   x x-ray

  32  Maxwell's Theory of Electromagnetism
   x predicted the speed of light
      was known to Newton
      has been found to be incomplete
      was developed in 1965
      contains Newton's laws

  33  Destructive interference is a signature of
      laser light
      acoustical waves
   x all forms of waves
      particle collisions
      impedance in materials

  34  The change in color of a hot body as it is heated is predicted by
   x Wien's law
      Stefan's law
      Snell's law
      Bohr's law
      Newton's law

  35  The diffractive limit of a telescope is due to
      gravitational distortion
      chromatic aberration
      spherical aberration
   x the wave properties of light
      the energy carried by photons

  36  When light passes through a prism of glass,
      The prism absorbs colors from different parts of the broad beam coming-out of the prism, leaving the complementary colors that we see.
      The different colors are caused by multiple reflections in the prism and interference between the resulting beams.
      The prism adds colors to different parts of the broadly scattered beam coming out of it.
   x The different colors or wavelengths of light are separated in angle by the prism.

  37  Violet light differs from red light in that
      Violet light has a longer wavelength than red light.
      Violet light travels more slowly (through a vacuum) than red light.
   x Violet light has a shorter wavelength than red light.
      Violet light travels more quickly (through a vacuum) than red light.

  38  On the absolute scale of temperature (in kelvins), the zero of the scale corresponds to
   x The temperature at which motions of atoms and molecules essentially cease
      The melting point of ice
      The mean temperature of space.
      The freezing point of hydrogen

  39  An example of an object that emits no radiation at all is
   x Any object at a temperature of 0 K
      Any object made of ice
      Any object with the temperature of outer space
      Any blackbody

  40  Pieces of metal are heated by varying amounts in a flame. The hottest of these will be the one that shows which color most prominently?
   x Blue

  41  Where and by what technique was the element helium first discovered?
      In the upper atmosphere of Earth, by studying the aurora, or northern lights
      In radioactive rocks from uranium deposits
      In the laboratory, by heating chemicals in a flame
   x On the Sun, from spectroscopy during a solar eclipse

  42  The chemical makeup of a star's surface is usually inferred
      By theoretical methods, considering evolution of the star
      By measuring the chemical elements present in the solar wind
      By taking a sample of that surface with a space probe
   x By spectroscopy of the light emitted by the star

  43  What happens in general when ultraviolet radiation passes through a tube of cool hydrogen gas?
   x All of the radiation passes through the tube except for specific wavelengths, which are absorbed by the atoms.
      All of the radiation will be absorbed completely.
      Some of the radiation at all wavelengths is absorbed, reducing the intensity at all wavelengths uniformly.
      All of the radiation passes through the tube unhindered because the hydrogen gases cool and cannot absorb energy.

  44  Changes in the observed wavelength of light due to the Doppler effect occurs
      Only when the temperature of an object changes
      Whenever the light source is moving with respect to the observer (regardless of direction)
      Only when the light source has a proper motion (across the line of sight)
   x Only when the light source has a radial velocity (toward or away from the observer)

  45  Which characteristic property of a glass lens is the most important in bending light rays to form a focused image?
      The color of the glass
   x The curvature and shape of its surfaces
      The diameter or size of the lens
      The thickness of the center of the lens

  46  When light in air or a vacuum enters the plane surface of a dense transparent medium at an angle to the perpendicular to this surface, which way does the light ray bend?
      It does not bend at all, because the material is transparent.
   x It bends toward the perpendicular.
      It bends so that whatever the incoming angle, the light always travels along the perpendicular to the surface.
      It bends away from the perpendicular.

  47  Who was the first astronomer to build and use a telescope to observe the moons of Jupiter?
      Tycho Brahe
   x Galileo

  48  The main reason for building larger optical telescopes on the Earth's surface is
      To improve the resolution of astronomical objeces
      To better magnify images of astronomical objects
   x To collect more light from faint objects
      For national prestige, with no good scientific reason

  49  Colors are perceived differently by our eyes because of their different:
   x Wavelengths.

  50  Space travelers looking out from the front of their accelerating spacecraft would note that the light emitted from the star system toward which they were moving seemed to be:
      Getting redder.
   x Getting bluer.
      Staying the same.

  51  Which of the following types of visible light has the highest energy?
   x violet

  52  What is emitted from an atom when one of its electrons makes a transition from a higher energy state to a lower energy state?
   x photon