Astronomy Chapter 3

How does the speed of light in a substance such as glass compare with the speed of light in a vacuum?

The speed of light in glass is slower than the speed of light in a vacuum

What is the one fundamental difference between X-rays and radio waves?

The wavelengths of X rays and radio waves are very different.

The spectrum of sunlight, when spread out by a spectrograph, has which characteristic appearance?

continuous band of color, crossed by innumerable dark absorption lines

The chemical makeup of a star s surface is usually inferred by

spectroscopy of the light that emitted by the star

In which of the following parameters does a photon of blue light NOT differ from a photon of yellow light, in a vacuum?

speed

Which of the following wavelength regions MUST be observed from space because almost no energy in this region reaches the ground?

x rays

What is a neutron?

an uncharged particle similar in mass to a proton

The basic makeup of an atom is

small, negatively charged particles orbiting around a central positive charge

The isotope 20Ne is 10th in the periodic table. The nucleus of this isotope contains _____ protons and _____ neutrons.

10 protons and 10 neutrons

One nanometer (nm) is equal to:

10-9 m.

How many electrons surround the nucleus of a neutral atom of iron, the 26th element in the periodic table?

26

The normal temperature of the melting point of water ice is

273 K

The speed of light is

3 × 10^8 m/sec.

Visible wavelengths of electromagnetic radiation have a range of wavelengths of

400 nm to 700 nm.

What is a CCD (charge-coupled device)?

An array of small light-sensitive elements that can be used in place of photographic film to obtain and store a picture

Which of the following statements is TRUE if the star Betelgeuse has a lower surface temperature than the Sun? (Assume that IR means infrared radiation and UV means ultraviolet radiation.)

Betelgeuse emits less IR and less UV flux than the Sun.

A beam of light of which of the following pure colors is made up of photons of the highest energy?

Blue

The temperature scale MOST often used by scientists is the

Kelvin scale

Who first showed that light does NOT travel at infinite speed?

Ole Rømer in 1675

If two photons in a vacuum have different energies, what can we say about the wavelengths of the photons?

The higher-energy photon has the shorter wavelength

A scientist reports that his measurement of the temperature of the surface of a newly discovered planet is 20 K. What conclusion can you draw from this report?

The result is erroneous because absolute temperature cannot be negative

What is the relationship between color and wavelength for light?

Wavelength increases from violet to red.

In a telescope, to what does the term aberration refer?

a defect in design that blurs or distorts the image

The light from a small amount of a particular chemical element, when heated in a flame, is found to consist of a:

a pattern of narrow, bright emissions at wavelengths that are specific to the element and different for each element

Atoms in a low-density, hot gas (e.g., in a fluorescent lamp or a neon tube) emit a spectrum that is

a series of specific colors unique to the type of atom in the tube but fixed in position when the gas temperature changes

The neutron is the electrically neutral particle that, along with the proton, makes up the atomic nucleus. The mass of the neutron, compared with that of the proton, is

about the same

A perfect blackbody is so named because it:

absorbs all radiation falling upon it and reflects none.

The major cause of blurred and unsharp images of objects observed through very large telescopes at the extreme limit of magnification is the

air turbulence in the Earth's atmosphere.

Compared with the mass of an electron, the mass of a proton is

almost 2000 times greater

Ionization of an atom occurs when

an electron is removed from the atom.

An atom in which one or more electrons has been removed is known as a(n):

an ion

The MAIN reason that the angular resolution of a 20-m-diameter radio telescope is worse than that of a 0.5-m-diameter optical telescope is that

angular resolution becomes worse as wavelength increases

The light-gathering power of a telescope depends directly on the

area of its primary mirror or lens

Telescopes are placed in space to view distant galaxies PRIMARILY to:

avoid the absorption and distortion of the light or other radiations within the atmosphere of the Earth

Visible light occupies what position in the electromagnetic spectrum?

between infrared and ultraviolet radiation

Pieces of metal are heated by varying amounts in a flame. The hottest of the pieces will be the one that shows MOST prominently which color?

blue

What is refraction of light?

change in direction of a light ray as it passes at an angle from one transparent material to another that has a different optical density

In 1670, Isaac Newton performed a crucial experiment on the nature of light when he:

demonstrated that white light was made up of colors that could be split by a prism and that these colors were not produced by the glass through which the light passed

The physical force that holds the components of an atom together is the:

electromagnetic attraction between the positive nucleus and the negative electrons

Consider a beam of electromagnetic radiation of a single frequency. The energy of each photon in this beam depends on each of the following properties of the beam EXCEPT ONE. Which is the exception?

intensity

radio telescope

is very similar to a reflecting optical telescope.

In Bohr s model of the hydrogen atom, light is emitted whenever an electron

jumps from an upper to a lower energy level or orbit.

Thomas Young demonstrated that light behaves as a wave by showing that:

light passing through two narrow, closely spaced slits produces a pattern of light and dark bands on a screen by wave interference.

What factor has seriously reduced the effectiveness over the last few years of the 5-m Hale telescope on Mt. Palomar, California, formerly the largest telescope in the world?

light pollution from nearby cities

The Doppler effect is the change in the wavelength of light caused by the source

moving with respect to the observer.

The position of an element in the periodic table, its atomic number, is equal to the

number of protons in the nucleus of the atom.

The radial velocity of a star or other object is measured by

observing the Doppler shift of spectral lines in the light from the object

The BEST Earth-based sites for modern large astronomical telescopes, which provide the least seeing effects on astronomical images, are

on the tops of high mountains, above a large fraction of the disturbing atmosphere.

Chromatic aberration is the failure of a telescope objective to bring all colors of light to the same focus and appears in:

only a refracting telescope.

What is a diffraction grating?

piece of glass with thousands of closely spaced, parallel grooves

Isotopes of a particular element in the periodic table have the same number of _____ in the nucleus.

protons but different numbers of neutrons

In the 1860s, James Clerk Maxwell carried out important investigations on the nature of light when he

proved mathematically that light could be described by oscillating electric and magnetic fields

The Hubble space Telescope is NOT designed to investigate

radio waves

Which of the following types of electromagnetic radiation has the longest wavelength?

radio waves

A beam of light of which of the following pure colors is made up of photons of the lowest energy?

red

When light passes through a prism of glass,

refraction changes the directions of different colors or wavelengths of light.

Cepheid variable stars pulsate regularly in size. During the contraction part of the cycle, when the star s temperature is increasing, the peak wavelength of the emitted radiation will

shifts from the visible to the UV part of the spectrum

Which of the following characteristics of an astronomical telescope is the MOST important for determining the angular resolution?

the diameter of the objective lens or mirror

X-rays and visible light are

the same thing except that X rays have shorter wavelengths than visible light.

The distribution of radiation emitted by a blackbody (i.e., its spectrum) depends on which one of the following properties of the blackbody?

the temperature

According to modern atomic theory, light emitted by atoms originates from

transitions of electrons between electron levels of the same atom.

In which one of the following ranges of the electromagnetic spectrum do photons have the MOST energy?

ultraviolet

Which of the following sequences of electromagnetic radiation is CORRECT, in order of increasing energy of the photons (or quanta)?

visible light, UV radiation, X-rays, gamma rays