Astrology Exam 2

The angular resolutions of the largest single-dish radio telescope in the United States, the 300-ft Green Bank Telescope, is ________ when it operates at a wavelength of 20 cm.

0.12 degrees

The n = 5 electronic energy level in a hydrogen atom is 1.5 x 10 -19 J higher than the n = 3 level. If an electron moves from the n = 5 level to the n = 3 level then a photon of wavelength

1,300 nm, which is in the infrared region, is emitted

How do the wavelength and frequency of red light compare to the wavelength and frequency of blue light?

Red light has a longer wavelength and lower frequency than those of blue light

What is the surface temperature of a star that has a peak wavelength of 290 nm?

10,000 K

At what approximate wavelength does your body radiate the most given that your temperature is approximately that of the Earth, which is 300 K?

10^-5 m

Compare two blackbody objects, one at 200 K and one at 400 K. How much larger is the flux from the 400 K object, compared to the flux from the 200 K object?

16 times as much

The diffraction limit of a 4-m telescope is _______ than that of a 2-m telescope.

2 times smaller

A red photon has a wavelength of 650 nm. An ultraviolet photon has a wavelength of 250 nm. The energy of an ultraviolet photon is _______ than a red photon.

2.6 times larger

What is the ratio of the orbital angular momentum (OAM) of Jupiter to its spin angular momentum (SAM)? Jupiter's orbit has a semimajor axis of 5 AU and period of 12 years, and Jupiter has a rotation period of 0.4 day and a radius of 70,000 km. Formula for OAM is L/orbital = m r v. Formula for SAM is L/spin = 4nmR2/5 P (R=radius of object, P=period).

26 thousand

The average red giant in the night sky is about 1,000 times more luminous than the average main-sequence star. If both kinds of stars have about the same brightness, how much farther away are the red giants compared to the main-sequence stars?

33 times farther

What wavelengths of light can the human eye see?

380 nm to 750 nm

The light-gathering power of a 4-m telescope is _______ than that of a 2-m telescope. HINT: Here the numbers refer to the diameter of the lens gathering the light. The light-gathering power is proportional to the area of the lens.

4 times larger

Light with a wavelength of 600 nm has a frequency of...

5.0 x 10 14 Hz

You record the spectrum of a star and find that the calcium absorption line, whose rest wavelength is 393.3 nm an observed wavelength of 394 nm. What is the radial velocity of this star?

500 km/s

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 are equally luminous. Star C is twice as far away from Earth as star D. How do the brightness level of stars C and D compare?

Star D appears four times as bright as star C

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

The frequency would be two times lower

How does the resolution of a telescope depend on its focal length?

The longer the focal length, the better the resolution

Heisenburg's uncertainty principle tells us that an electron in an atom behaves like...

a cloud

If you observe a star, you will see

an absorption spectrum

The Kelvin temperature scale is used in astronomy because...

at 0 K an object has absolutely zero energy

Light has aspects of...

both a particle and a wave

Saying that something is quantized means that it...

can only have discrete quantities

As wavelength increases, the energy of a photon ______ and its frequency_______.

decreases; decreases

Astronomers usually study distant objects by looking at them directly through the eyepiece of a telescope.

false

One of the reasons why the Hubble Space Telescope has better spatial resolution that a 4-m ground-based telescope is that it has a larger mirror.

false

The centripetal force in a collapsing cloud of gas and dust is strongest at the Poles

false

The path of red light is deflected by a larger angle than blue light when passing through a glass prism

false

Which of the following lists different types of electromagnetic radiation in order of increasing wavelength?

gamma rays, ultraviolet, visible, infrared, radio waves

Comets and asteroids are...

material left over from the formation of the planets.

As a blackbody becomes hotter, it also becomes __________ and __________.

more luminous; bluer

Conservation of angular moment slows a cloud's collapse...

mostly along directions perpendicular to the cloud's axis of rotation.

When we determine the angular resolution of an interferometric array of radio telescopes using the formula q u I/D, the variable D stands for...

separation between the telescopes.

According to the conservation of angular momentum, if an ice skater starts spinning with her arms out wide, then slowly pulls them close to her body, this will cause her to...

spin faster

A black car left in the sunlight becomes hotter than a white car left in the sunlight under the same conditions because...

the white car reflects more sunlight than the back car

Absorption spectra are observed when a cooler gas is in between you and a source that has a higher temperature than the surrounding gas.

true

All planets orbit the Sun in the same direction.

true

Continuous spectra are produced by viewing a hot glowing object.

true

Emission spectra are observed when you see a hot gas directly.

true

Planets like Earth are found closer to the Sun than planets like Jupiter.

true

The angular momentum of a planet depends on its mass and its distance from the Sun.

true

The dispersing element in a spectrograph could be a prism or a diffraction grating.

true

The image quality of most optical telescopes is limited by differential atmosphere refraction experienced my light as it passes through the Earth's atmosphere.

true

To date astronomers have not yet detected Earth-size planets around normal stars.

true

Two bodies of equal moment of inertia are rotating in the same direction and the same angular velocity (w) around a common axis and at the same distance (r) from the axis of rotation. If the bodies suddenly coalesce together at the same distance (r) from the axis of rotation, their final angular velocity (w) will be...

w