Astronomy Hmwk 3

A cool, dilute gas between an observer and a continuous hot source will produce which of the following effects? A. The peak of the continuous spectrum will be shifted toward higher frequencies. B. The peak of the continuous spectrum will be shifted toward lower frequencies. C. Dark absorption lines will appear in the spectrum. D. Bright emission lines will appear in the spectrum. E. The spectral lines will be broadened by the heat from the source.

C

A total lunar eclipse occurs: A. During a new moon phase B. When the sun blocks the moon C. During a full moon phase D. Always around the summer solstice

C

The Orion Nebula, M-42, is a hot, thin cloud of glowing gas, so its spectrum is A. a few dark lines in the continuum. B. not in the visible portion of the spectrum. C. a few bright lines against a dark background. D. a continuum, strongest in the color red. E. a continuum, but with both bright and dark lines mixed in.

C

What type of spectrum is emitted by a low-density luminous cloud of hot gases? A. Continuous B. Absorption C. Emission D. All of the types listed here E. None of the types listed here

C

Which of the following is NOT one of Kirchhoff's laws? A. A low-density, cool gas absorbs photons from a continuous source, creating an absorption spectrum. B. A low-density, hot gas emits an emission spectrum. C. A low-density, cool gas in isolation creates a continuous spectrum. D. A luminous solid, liquid, or dense gas emits a continuous spectrum.

C

(T/F) As a star's temperature increases, the frequency of peak emission also increases.

T

(T/F) The absorption lines for a cool thin gas are identical in color and energy to the emission lines of the same gas if hot enough to glow.

T

(T/F) The spectral lines of each element are distinctive to that element, whether we are looking at emission or absorption lines.

T

The number of ___________ identifies the type of element.

protons

As they are heated from low to high temperature, solid objects will appear to glow in which of the following sequences of colors? A. Red, reddish-yellow, then white B. White, red, then yellow C. Red, blue, then green D. Blue, green, yellow, then red

A

If a hydrogen atom encounters a photon of energy, what will its electron do? A. Absorb the photon only if it has the exact energy needed to move to another energy level B. Absorb only as much of the photon's energy as it needs to move to the next energy level C. Ignore the photon so it can remain in the ground state, the state of lowest energy D. Absorb the photon and jump to whatever position corresponds to its new energy

A

The shape of a blackbody curve depends on what single property of the blackbody? A. Temperature B. Total brightness C. Density D. Composition

A

What is TRUE of a blackbody? A. Its energy peaks at the wavelength determined by its temperature. B. It has a complete absence of thermal energy. C. It appears black to us, regardless of its temperature. D. Its energy is not a continuum. E. If its temperature doubled, the peak in its curve would be doubled in wavelength

A

What is the most obvious and important way in which the characteristic spectra of atoms differ from those of molecules? A. Molecular spectra are generally far more complex than the characteristic spectra of the atoms of which they are composed. B. Molecular spectra fade more quickly with distance than do atomic spectra. C. Molecular spectra are much brighter than the characteristic spectra of the atoms of which they are composed. D. Molecular spectra are generally far simpler than the characteristic spectra of the atoms of which they are composed. E. Molecular spectra are much dimmer than the characteristic spectra of the atoms of which they are composed.

A

Stars like our Sun emit most of their light in which part of the electromagnetic spectrum? A. The X-ray B. The visible C. The infrared D. The ultraviolet E. The radio

B

A neon light (thin hot neon gas in a sealed tube) gives us A. a continuous spectrum, since the neon is hot enough to glow. B. a continuum, with dark lines identifying the neon atoms that are present. C. a lot of random bright red lines due to the motion of the hot atoms. D. a few bright emission lines, telling us the gas is neon. nothing visible to us, but a lot of infrared lines as heat.

D

The temperature scale that places zero at the point where all atomic and molecular motion ceases is A. Centigrade. B. Fahrenheit. C. Ransom. D. Kelvin. E. Celsius.

D

(T/F) In blackbody radiation, the energy is radiated uniformly in every region of the spectrum, so the radiating body appears black in color.

F

(T/F) The red hydrogen alpha line carries more energy per photon than the blue-green hydrogen beta line does.

F

The number of __________ identifies whether an atom carries a charge as an ion or is neutral.

electrons