ASTR 1000 Chapter 5 (Midterm)

The speed of light in a vacuum is

300,000 km/s.

Light has aspects of

both a particle and a wave.

Which formula denotes how the speed of light is related to its wavelength and frequency?

c = λf

The amplitude of a wave is

the maximum height of the wave above zero.

When referring to a wave, what does the term medium refer to?

the substance through which the wave travels

If the wavelength of a beam of light were to double, how would that affect its frequency?

The frequency would be two times lower.

What is the difference between visible light and X-rays?

Wavelength; X-rays have a shorter wavelength than visible light.

Which wavelength range of light is visible to the human eye?

380–750 nm

Which of the following lists different types of electromagnetic radiation in order from the shortest wavelength to the longest wavelength?

gamma rays, ultraviolet, visible, infrared, radio waves

The wavelength ranges of light that are immediately on either side (in terms of wavelength or frequency) of the visible spectrum are

ultraviolet and infrared.

The color of visible light is determined by its

wavelength.

Which of the following photons carries the smallest amount of energy?

a microwave photon, whose wavelength is 10^–2 m

Saying that something is quantized means that it

can only be found in discrete quantities.

As wavelength increases, the energy of a photon ________, and its frequency ________.

decreases; decreases

If the frequency of a beam of light were to increase, its period would ________, and its wavelength would ________.

decrease; decrease

The frequency of a wave is

the number of peaks that pass per second.

When an electron moves from a higher energy level in an atom to a lower energy level,

Which of these objects would emit an absorption spectrum?

a thin, cool gas cloud that lies in front of a hotter blackbody

If you observe the spectrum of a single star located in otherwise empty space, you will see

a continuous spectrum with absorption lines.

In the energy-level diagram shown in the figure below, the electron is excited to the E₄ energy level. If the electron transitions to an energy level giving off a photon, which level would produce a photon with the highest amount of energy?

E₁

In the energy-level diagram shown in the figure below, the electron is excited to the E₄ energy level. If the electron transitions to a new energy level giving off a photon, which level would produce a photon with the largest frequency?

E₁

In the energy-level diagram shown in the figure below, the electron is excited to the E₄ energy level. If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest wavelength?

E₃

In the energy-level diagram shown in the figure below, the electron is excited to the E₂ energy level. If the atom absorbs a photon with the exact frequency to move the electron to another energy level, which energy level would correspond to the incoming photon with the largest frequency?

E₅

In the energy-level diagram shown in the figure below, the electron is excited to the E₂ energy level. If the atom absorbs a photon with the exact wavelength to move the electron to another energy level, which energy level would correspond to the incoming photon with the largest wavelength?

E₃

What fundamentally distinguishes an iron atom from a carbon atom?

An iron atom has more protons in its nucleus than a carbon atom.

In the quantum mechanical view of the atom, in contrast with the Bohr model, electrons are depicted as

a cloud that is centered on the nucleus.

A spaceship is traveling toward Earth while giving off a constant radio signal with a wavelength of 1 m. What will the signal look like to people on Earth?

a signal with a wavelength of less than 1 m

Which of these stars would have the largest positive redshift?

a star moving at high speed away from you

You observe the spectrum of two stars. Star A has an emission line from a known element at 600 nm. Star B has emission lines from the same atom, but the emission line occurs at 650 nm. One possible explanation for this observation is that star B is

moving away from us faster than star A.

If the quantity of something entering a system is equal to the quantity of that same thing leaving that system, we say that the system is

in equilibrium.

What does it mean to say that an object is in thermal equilibrium?

It is absorbing the same amount of energy that it is radiating.

The Kelvin temperature scale is used in astronomy because

at 0 K, an object has zero thermal energy.

As an object’s temperature increases, the atoms inside that object

move at higher velocities.

In the figure below, which blackbody spectrum corresponds to the object with the highest temperature?

A

In the figure below, which blackbody spectrum corresponds to the object that would appear reddest to the human eye?

C

In the figure below, which blackbody spectrum corresponds to the object that would appear white to the human eye?

A

As a blackbody’s temperature increases, it also becomes ________ and ________.

more luminous; bluer

Why do some stars in the sky appear blue, whereas other stars appear red?

The blue stars have higher surface temperatures than the red stars.

Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare?

Star A is four times as luminous as star B.

Star C and star D have the same luminosity. Star C is twice as far away from Earth as star D. How do the brightness levels of stars C and D compare in Earth’s sky?

Star D appears four times as bright as star C.

If a lit lightbulb is moved twice as far away, its luminosity will be

the same.

Which of these planets would be expected to have the highest average temperature?

a dark-colored planet close to its star