What is the speed of light? Correct answer- Light can travel enormous distances under
short periods of time. It is faster than any other phenomenon. It takes about 8 minutes
for light to travel from the Sun to Earth. The speed of light in a vacuum is c=3x10^8 m/s.
Why is light such an important ...
why is light such an important tool for astronomers
how are different kinds of light waves arranged in the em spectrum
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PHY 102 Final Exam
What is the speed of light? Correct answer- Light can travel enormous distances under
short periods of time. It is faster than any other phenomenon. It takes about 8 minutes
for light to travel from the Sun to Earth. The speed of light in a vacuum is c=3x10^8 m/s.
Why is light such an important tool for astronomers? Correct answer- Because light is
how we learn about distant objects without travelling there. It is also a measuring took of
astronomy. Light is a wave and a particle.
How are different kinds of light waves arranged in the EM spectrum? Correct answer-
Light is arranged on the electromagnetic (EM) spectrum from shortest wavelength
(highest energy) to longest wavelength (lowest energy). The longer the wavelength the
safer it is for people to be around. Gamma rays have the shortest wavelength and are
used for cancer radiation. X-Rays are used for medical examinations. Infrared radiation
is used in a TV remote, microwaves are used in microwave ovens, and the radio waves
are used in mobile phones. They are arranged by frequency.
What is the relationship between frequency, color, wavelength, and energy? Correct
answer- Color is how our eyes distinguish frequency. Speed of light equals frequency
times wavelength. If frequency gets big then wavelength gets smaller and vice versa.
E=hf means if energy gets larger so does frequency (because h is a constant).
Frequency and wavelength are connected by speed of light. If you know one of
c=f(lambda) then you are able to calculate them all.
What do these equations express? c=f(lambda) and E=hf? Correct answer- c=speed of
light, f=frequency, lambda=wavelength, C=f(lambda) is the equation of speed of light.
For E=hf, E=photon's energy, h=Planck's constant (6.67x10^-34 J) and f=frequency,
This is the equation for measuring a photon's energy.
What are the characteristics of a good scientific theory? Correct answer- Good science
involves building upon existing knowledge, can be modified when new information is
found, has predictive power, develops step-by-step, is objective, and can be tested and
disproved. Scientific method steps: observe, hypothesize, predict, test, modify, and
simplify. It has predictability, it can be done repeatedly, and should be objective.
What might cause a scientific theory to be changed or abandoned? Correct answer- If
the theory is not testable or if it has been disproved numerous times. It would also be
abandoned if it is a pseudoscience which means it is based off of non-developing facts
or it is unable to be tested.
What is the difference between a science and a pseudoscience? Correct answer-
Science is a process and is testable and falsifiable, while a pseudoscience is usually
,impossible to disprove and rarely has new developments. A pseudoscience has no test-
ability, therefore it is not a science.
What units, and what size scales are needed to measure the universe? Correct answer-
Science is generally done in the metric system, and different units are used for different
measurements?
Why do stars, Sun, Moon and planets all appear to rise and set in our sky? Correct
answer- Because of the way the Earth rotates on its axis. Depending on where you are
on Earth, the movements of the stars appear somewhat different.
What is the Celestial Sphere? How is the coordinate system set up? What are some of
the major features on the celestial sphere? Correct answer- The celestial sphere is a
fixed coordinate system to model and map the sky: an imaginary sphere surrounding
the Earth in which all objects in the sky can be located. It has 2 axis points, the north
and south celestial poles (located directly above Earth's poles). There is also a celestial
equator (directly above Earth's equator). Longitude is measured in "right ascension" (in
hours), latitude is "declination" (in degrees, minutes, and seconds), and zero is the
celestial equator.
What is the correct explanation for the phases of the Moon? Correct answer- The
relative angle between the Sun, Moon, and Earth changes, illuminating the Moon's face
differently.
What is the correct explanation for the seasons on Earth? Correct answer- Earth's axis
is tilted 23.5 degrees with respect to its orbit around the Sun. The tilt changes the
seasons.
What is the cause of an eclipse? What kinds of eclipses are there? Correct answer-
There are lunar eclipses (when the moon enters the shadow of the Earth). There are 3
types of lunar eclipses. There is the penumbral eclipse (when the moon enters the
penumbra of the Earth's shadow) which is not very noticeable, a partial eclipse (when
the moon is partially in the umbra), and the moon is half dark, and a total lunar eclipse
(when the whole Moon is in the Earth's umbra) and the moon looks red. There are also
solar eclipses (when the moon completely surpasses the sun). There are partial solar
eclipses (when the sun is only partially covered by the moon), and Annular solar
eclipses (when the Moon's umbra falls short of the Earth, the moon appears too small to
cover the Sun), these leave a thin ring, "annulus" of light around the moon.
What is the definition of velocity? How is it related to distance and time? Correct
answer- Velocity is defined as "a quantity that specifies both direction and speed of an
object." It is related to distance and time because the equation for velocity is
velocity=distance/time, meaning that distance divided by time make up velocity.
What is the definition of acceleration? How is it related to velocity, distance, and time?
Correct answer- A=V/t Acceleration is defined as "a charge in the direction or magnitude
, of a velocity." It is related to velocity, distance, and time because the equation for
acceleration is a=(delta) v/t, meaning that acceleration is the change in velocity (and
distance factors into velocity) divided by time.
What does this equation express? v=vo +at Correct answer- This equation means:
velocity=intial velocity +constant x time.
What does this equation express? x=x0+v0t+½ at^2 Correct answer- This is a
kinematics equation meaning: distance=initial displacement + initial velocity x time +
constant x time squared. X is a distance or position X0 is initial position, V0 is initial
velocity. This equation figures out where an object will be after certain time, velocity and
with its initial position.
What property makes an atom unique, as opposed to other divisions of matter? Correct
answer- It is because it is the smallest chemical properties? Each chemical element has
it's own type of atom, and if you break an atom up more it would not be that element
anymore.
What is the structure of an atom? What are its constituent parts? What are the main
features of the Bohr model of an atom? Correct answer- The modern view (Bohr model)
has energy levels that are very rigid and unique, energies in electrons are quantized
meaning they can only have certain energy levels. Nucleus has protons and neutrons
and the number of protons tells the chemical element while the number of neutrons tells
the isotopes. Farthest electron has maximum energy on the KLMN. Electrons can jump
to different levels if turned on
What is an energy level in an atom? How do electrons move between them? Correct
answer- This is part of Bohr's model, and the energy level is how much energy an
electron has. Physicists used to care about the placement of an electron, but lately they
decided that placement does not matter as much as energy level. Electrons can only
move energy levels if the exact amount of energy needed comes along. It was
described like stairs, where you can't stand between 2 stairs, you either have to be on
one or the other.
What types of atoms are most important in studying astronomy? Correct answer-
Hydrogen and helium because they are most abundant. 90% of the universe is
hydrogen and 9% is helium.
What are galaxies made of? Correct answer- They are made of hydrogen, helium,
simple carbon compounds, and most importantly gas and dust. These form stars and
clouds of gas and dust that are lit up by dust or will obscure the light from the stars.
How are galaxies classified? What type of galaxies are there? Correct answer-
Classified by Edwin Hubble by how big they were through a telescope. Elliptical, Spiral,
spiral barred, and irregular
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