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Astronomy 207 (ASTR 207) Midterm 3 –
2026/2027 Study Edition | Complete
Practice Questions & Answers | Grade A
Astronomy Review
What is power?
the rate of energy flow (in watts)
What is 1 watt in joules?
1 watt = 1 joule per second
What are the primary colours of vision?
red, blue and green
What are two ways to break white light into a continuous rainbow spectrum?
prism or diffraction grating
What are the 4 ways light interacts with matter?
1. emission: ex. a light bulb emits visual light by converting electrical potential energy into
radiative
2. absorption: ex. placing hand near a light bulb, opaque objects
3. transmission: light passes through material (like a window
4. reflection(in one direction)/scattering(in all directions): light bounces off matter ex. when
seeing a colour
How did Issac Newton prove that colours come from light?
he placed a second prism in front of only the red light emitted by an initial prism. this second
prism emitted only red light, which prove that the rainbow was coming from the light, not the
prism
Who suggests light was made of particles?
Newton
How are electromagnetic waves light waves?
light waves are travelling vibrations of electric and magnetic fields: these fields make electrons
bob up and down like a leaf on a rippling pond. the light travels but the electrons do not
What is a field?
the strength of force that a particle would experience at any point in space
,What are photons?
particles of light, each with a wavelength, frequency and energy
What does the radiation danger of a photon depend on?
energy (which depends on frequency)
Why is Planck's constant such a small number?
because of the sheer volume of photons in light
What are the types of light in the electromagnetic spectrum, in order of increasing frequency and
their wavelengths?
radio (1m), micro (part of radio), infrared, visible (400-700nm/10^-6m), UV, X-ray, gamma
(10^-12m)
What is a major difference between types of light on the electromagnetic spectrum?
diff portions interact with matter differently: for example, radio waves pass through walls while
visible waves don't
What is the origin of the word "atom"?
Democritus created the term from the Greek word meaning "indivisible" (atoms are in fact
divisible)
What makes up most of the mass of an atom?
nucleus
What makes up most of the volume of an atom?
electron cloud
What is the number of atoms in a single drop of water?
10^22 - 10^23, possibly exceeding the number of stars in the observable universe
What is an element?
a type of atom, over 100
What charge are ordinary atoms?
neutral
How are atoms held together?
attraction between positive nucleus and negative electrons
, What is the atomic mass number?
number of protons and neutrons in nucleus
What is the atomic number?
number of protons in nucleus
What are isotopes?
atoms of the same element with different numbers of neutrons
What are ions?
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
What are molecules?
two or more atoms bonded together
What causes the illusion of solidity?
electrical interactions between charged particles and strange quantum laws of electrons
When do phase changes occur?
when one type of bond is broken and replaced by another, differing in strength
What two things can cause a phase change?
temperature and pressure
How does temperature cause a phase change?
(molecules are always vibrating to some degree) as the temp increases, the average kinetic
energy of the particles increases, enabling them to break bonds
What is the relationship between solid, gas, and liquid?
have the same bond but different strengths
When can matter be in multiple phases at once and why does this occur?
there is always some vapourization over water (evaporation) and ice (sublimation), because the
temperature is only the average kinetic energy - individuals particles may have a higher
temperature and can escape from a solid/liquid
What are the stages of matter that water goes through as the temperature is raised and their
temperatures?
solid (0 degrees/273K and below), liquid, gas (hundreds of K), molecular dissociation (thousands
of K), plasma phase (tens of thousands of K), fully ionized plasma (millions of K)
Astronomy 207 (ASTR 207) Midterm 3 –
2026/2027 Study Edition | Complete
Practice Questions & Answers | Grade A
Astronomy Review
What is power?
the rate of energy flow (in watts)
What is 1 watt in joules?
1 watt = 1 joule per second
What are the primary colours of vision?
red, blue and green
What are two ways to break white light into a continuous rainbow spectrum?
prism or diffraction grating
What are the 4 ways light interacts with matter?
1. emission: ex. a light bulb emits visual light by converting electrical potential energy into
radiative
2. absorption: ex. placing hand near a light bulb, opaque objects
3. transmission: light passes through material (like a window
4. reflection(in one direction)/scattering(in all directions): light bounces off matter ex. when
seeing a colour
How did Issac Newton prove that colours come from light?
he placed a second prism in front of only the red light emitted by an initial prism. this second
prism emitted only red light, which prove that the rainbow was coming from the light, not the
prism
Who suggests light was made of particles?
Newton
How are electromagnetic waves light waves?
light waves are travelling vibrations of electric and magnetic fields: these fields make electrons
bob up and down like a leaf on a rippling pond. the light travels but the electrons do not
What is a field?
the strength of force that a particle would experience at any point in space
,What are photons?
particles of light, each with a wavelength, frequency and energy
What does the radiation danger of a photon depend on?
energy (which depends on frequency)
Why is Planck's constant such a small number?
because of the sheer volume of photons in light
What are the types of light in the electromagnetic spectrum, in order of increasing frequency and
their wavelengths?
radio (1m), micro (part of radio), infrared, visible (400-700nm/10^-6m), UV, X-ray, gamma
(10^-12m)
What is a major difference between types of light on the electromagnetic spectrum?
diff portions interact with matter differently: for example, radio waves pass through walls while
visible waves don't
What is the origin of the word "atom"?
Democritus created the term from the Greek word meaning "indivisible" (atoms are in fact
divisible)
What makes up most of the mass of an atom?
nucleus
What makes up most of the volume of an atom?
electron cloud
What is the number of atoms in a single drop of water?
10^22 - 10^23, possibly exceeding the number of stars in the observable universe
What is an element?
a type of atom, over 100
What charge are ordinary atoms?
neutral
How are atoms held together?
attraction between positive nucleus and negative electrons
, What is the atomic mass number?
number of protons and neutrons in nucleus
What is the atomic number?
number of protons in nucleus
What are isotopes?
atoms of the same element with different numbers of neutrons
What are ions?
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
What are molecules?
two or more atoms bonded together
What causes the illusion of solidity?
electrical interactions between charged particles and strange quantum laws of electrons
When do phase changes occur?
when one type of bond is broken and replaced by another, differing in strength
What two things can cause a phase change?
temperature and pressure
How does temperature cause a phase change?
(molecules are always vibrating to some degree) as the temp increases, the average kinetic
energy of the particles increases, enabling them to break bonds
What is the relationship between solid, gas, and liquid?
have the same bond but different strengths
When can matter be in multiple phases at once and why does this occur?
there is always some vapourization over water (evaporation) and ice (sublimation), because the
temperature is only the average kinetic energy - individuals particles may have a higher
temperature and can escape from a solid/liquid
What are the stages of matter that water goes through as the temperature is raised and their
temperatures?
solid (0 degrees/273K and below), liquid, gas (hundreds of K), molecular dissociation (thousands
of K), plasma phase (tens of thousands of K), fully ionized plasma (millions of K)
