ASTR 102 Midterm

a typical chemical reaction releases about ______ of energy per atom

1 ev

Universe started expanding ______ years ago

13.7 billion

Once the distance to the Sun is measured, its diameter can be calculated with the...

small angle approximation

compared to an atom as a whole, an atomic nucleus is very _____ but has ______ of the mass

small, most

Graphical representation of Sun's visible light spectrum

smooth part of the curve represents graph of the background rainbow of color; dips in the curve represent the black lines where light is missing from the rainbow

Sublimation is the process by which ______ material enters the ______ phase

solid, gas

Each chemical element produces a unique set of _________

spectral lines

wavelength x frequency = __________

speed of light

Heavier elements subsequently forged in...

stars and supernova

in the bohr model of the atom, light is emitted only when...

an electron makes a transition from one orbit to a lower orbit

Shorter wavelengths mean

higher frequency

Blue light has a higher frequency than red light. Thus blue light has _____ energy and ______ wavelength than red light

higher, shorter

One of the laws of thermal radiation states that a _______ object emits photons with ________ average energy

higher-temperature, higher

The atom in which the electron leaves corresponds with the ________ energy proton, the atom with the shortest arrow indicates the case where the absorbed photon had the ______ energy

highest, lowest

In the beginning, the Universe was composed entirely of ______ and _______

hydrogen and helium

Where should you put a telescope designed for ultraviolet observations?

in Earth orbit

If you wanted a radio telescope to achieve the same angular resolution as a visible-light telescope, it would need to be:

much larger

Visible light spans only a very ________ narrow range of wavelengths.

narrow

A ______ charged zinc plate can be discharged when illuminated with ______ light.

negatively, ultraviolet

Neon appears reddish-orange because

neon atoms emit many more yellow and red photons than blue and violet photons

What powers the sun?

nuclear fusion

the photons of light interact with the electrons in the photoelectric effect...

one at a time

Suppose that two stars are separated in the sky by .01 arc second. If you look at them with a telescope that has an angular resolution of .5 arc second, what will you see?

one point of light that is the blurred image of both stars

How would you make a spectrum of the sun?

pass a narrow beam of sunlight through a prism

Overlaying gas of sun acts like a cloud to...

produce absorption lines

In the Bohr model of the atom, orbits are...

quantized

color light longest wavelength visible light?

red light

A spectral line that appears at a wavelength of 321 nm in the lab appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is

redshifted

A spectral line that appears at a wavelength of 321 nm in the lab appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:

redshifted

Wien's law states that the thermal radiation from a hotter object peaks at a __________ wavelength

shorter

Higher energy means...

shorter wavelength

The fact that the Sun's spectrum appears brightest in the yellow-green region tells us that

the approximate temperature of the Sun's surface

Radar can be used to determine....

the distance to a planet

The farther a photon is from an atom...

the greater the energy

Wien's law states that

the peak wavelength of a spectrum is directly related to an object's temperature

All forms of light move at ________ speed

the same

Emitted photon must have ______ of energy that the electron loses in moving from the _______ to the _______ energy level

the same, higher, lower

If you heat a rock until it glows, its spectrum will be a __________ _______ spectrum

thermal radiation

A spark can be more easily produced in a circuit if it was illuminated with ______ light, but not _____ light

ultraviolet, visible

A diffraction limit is a limit on...

a telescope's angular resolution

If you heat a rock until it glows, its spectrum will be:

a thermal radiation spectrum

How would you find what the Sun is made of?

Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory

Rank by wavelength from shortest to longest

Gamma X Rays Ultraviolet Visible Light Infrared Radio Waves

Emission Line Spectra from top to bottom

Helium Hydrogen Krypton Mercury Neon Water Vapor Xenon

An energy of a photon of light is proportional to its frequency

Planck's constant frequency

Rank by energy from lowest to highest

Radio Waves Infrared Visible Light Ultraviolet X Rays Gamma

Rank by frequency from lowest to highest

Radio Waves Infrared Visible Light Ultraviolet X Rays Gamma

Why does the Sun's spectrum contain black lines over an underlying rainbow?

Sun's hot interior produces a continuous rainbow of color, but cooler gas at surface absorbs light at particular wavelengths

How is an absorption line spectrum produced?

When continuous light from a hot source passes through a cooler cloud of gas

Absorption line spectrum shows what we see when we look at a hot light source directly behind...

a cooler cloud of gas

The twinkling of stars is caused by...

a motion of air in our atmosphere

For a higher temperature object, the graph peaks at ______

a shorter wavelength

The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:

above Earth's atmosphere

The Sun's spectrum is an __________ spectrum

absorption line

What type of visible light spectrum does the Sun produce?

absorption line spectrum

Which technology can allow a single ground-based telescope to achieve images as sharp as those from the Hubble Space Telescope?

adaptive optics

the fraction of incident light that is reflected away rather than absorbed

albedo

Re-emitted light is sent in _______ direction(s)

all

Rutherford's model of the atom: An _______ particle can be scattered through a _______ angle by the compact, ______ charged nucleus

alpha, large, positively

Thomson's model of the atom.. An _____ particle is scattered through only a ______ angle

alpha, small

Interferometry uses two or more telescopes to achieve

an angular resolution equivalent to that of a much larger telescope

Why does conservation of energy demand that it must re-emit light with the same total amount of energy?

because the cloud absorbs light from the hour source

The set of spectral lines that we see in a star's spectrum depend on the star's

chemical composition

The set of spectral lines that we see in a star's spectrum depends on the star's...

chemical composition

Interior of a sun produces a...

continuous spectrum

Compared to the Sun, a star whose spectrum peaks in the infrared is...

cooler

Compared to the Sun, a star whose spectrum peaks in the infrared is:

cooler

Blue light has higher frequency than red light. Thus, blue light has...

higher energy and shorter wavelength than red light

Radar cannot directly be used to...

determine the distance of the Sun

light comes in...

discrete packets of energy

The distance to the Sun can be calculated based on the...

distance to the planet Venus

If we're looking at the gas cloud but the light source is off to the side instead of directly behind it, the spectrum would be an...

emission spectrum

Stephan-Boltzman Law

energy flux

the rate at which energy is emitted from one square meter of the surface of a black body

energy flux

Why is energy order the same as frequency but opposite from wavelength?

energy of a photon of light is proportional to it's frequency

We determine the Sun's overall chemical composition by...

examining all the lines in its spectrum

How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?

four

wavelength times _______ equals the speed of light

frequency

Sun can be pictured as a _______ interior light source surrounded by a thin, cooler layer of ______

gas

earth reaches a "steady state" temperature when...

heat input equals heat output

Compared to an atom as a whole, an atomic nucleus...

is very tiny but has most of the mass

Some nitrogen atoms have 7 neutron and some have 8 neutrons which makes these two forms of nitrogen _______ of each other

isotopes

Some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are:

isotopes of each other

If you see the color red in an X-ray image from the Chandra X-Ray Observatory, it mans:

it depends: the colors are chosen arbitrarily to represent something about the X rays recorded by the telescope

Why is a sunflower yellow?

it reflects yellow light

Extra ______ energy of liberated electrons is proportional to the ______ of the incident light, not the _______.

kinetic, frequency, intensit

radio waves are a form of...

light

Longer wavelengths mean

lower frequency

Upper left portion of the solar spectrum shows the _____ visible light.

lowest frequency

brightness of sun x cross sectional area of earth =

luminosity of Earth

Sun's spectrum appears brightest in the _________ region

yellow-green