(5.) Physics Hl/Sl. Quantum And Nuclear Physics / Astrophysics
Quiz on physics section 13 and astrophysics, focusing on definitions. Don't screw up the definition questions! You getfree points if you just learn them.
Questions and Answers
- 1.
"Below a certain [...], no photoelectrons are emitted" Above, an aspect of the photoelectric effect is described. Which are the missing words?
Explanation
The missing words in the statement are "threshold frequency". The photoelectric effect is a phenomenon where electrons are emitted from a material when it is exposed to light. However, this emission only occurs when the frequency of the incident light is above a certain threshold frequency. Below this threshold frequency, no photoelectrons are emitted, indicating that the energy of the incident light is not sufficient to overcome the binding energy of the electrons in the material.Rate this question:
- 2.
The minimum energy required for electrons at a surface to escape is called the [...] of the metal
- A.
Threshold wavelength
- B.
Blue shift
- C.
Work function
- D.
Planck's constant
Correct Answer
C. Work functionExplanation
The work function refers to the minimum amount of energy that electrons need to overcome in order to escape from the surface of a metal. It is a characteristic property of each metal and can be thought of as the "energy barrier" that electrons must surpass to be emitted. The work function is typically measured in electron volts (eV) and is related to the binding energy of the electrons within the metal.Rate this question:
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- 3.
The dual nature of light is simply called "wave-particle duality"
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because the dual nature of light, which refers to its ability to exhibit both wave-like and particle-like properties, is indeed called "wave-particle duality". This concept is a fundamental principle in quantum mechanics and has been experimentally confirmed through various experiments and observations.Rate this question:
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- 4.
Is light a wave or is it a particle?
- A.
Wave
- B.
Particle
- C.
Yes
Correct Answer
C. Yes -
- 5.
"All moving particles have a "matter wave" with a wavelength associated with them" This hypothesis has a name. Which?
- A.
Davisson and Germer hypothesis
- B.
De Broglie hypothesis
- C.
Schrödinger hypothesis
- D.
Bainbridge hypothesis
Correct Answer
B. De Broglie hypothesisExplanation
The correct answer is de Broglie hypothesis. The de Broglie hypothesis, proposed by Louis de Broglie, states that all moving particles, including electrons and other subatomic particles, have a "matter wave" associated with them. This matter wave is characterized by a wavelength, which is inversely proportional to the momentum of the particle. This hypothesis was a significant development in the field of quantum mechanics and helped establish the wave-particle duality of matter.Rate this question:
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- 6.
Davisson and Germer conducted an experiment showing electron [...]
Correct Answer
diffraction - 7.
The description of particles (matter and /or radiation) in quantum mechanics is in terms of a(n) ...
- A.
Work function
- B.
Wave function
- C.
Orbital
- D.
Interpretation (the Copenhagen interpretation)
Correct Answer
B. Wave functionExplanation
In quantum mechanics, the description of particles is done using a wave function. The wave function represents the probability distribution of a particle's position and momentum. It provides information about the particle's behavior and properties, such as its energy levels and wave-like nature. The wave function is a fundamental concept in quantum mechanics and is used to calculate various physical quantities and make predictions about the behavior of particles. It is a mathematical function that contains all the information about a particle in a quantum system.Rate this question:
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- 8.
When a particle is observed, the wave function is said to [...]
Correct Answer
collapseExplanation
When a particle is observed, the wave function representing its possible states collapses into a single state. This means that the particle's position, momentum, or other observable properties become definite and no longer exist in a superposition of multiple possibilities. The collapse of the wave function is a fundamental concept in quantum mechanics, indicating the transition from a state of uncertainty to a specific outcome upon measurement. This collapse is a result of the interaction between the particle and the measuring apparatus, causing the wave function to "collapse" into a single outcome.Rate this question:
- 9.
The Copenhagen interpretation is a way to give a physical meaning to the mathematics of nuclear physics
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The Copenhagen interpretation is a way to give a physical meaning to the mathematics of wave mechanicsRate this question:
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- 10.
"Position and momentum cannot be measured simultaneously" "Energy and time cannot be measured simultaneously" These linked variables are known as conjugate quantities in the [...] uncertainty principle
- A.
Heisenberg
- B.
Bainbridge
- C.
De Broglie
- D.
Schrödinger
Correct Answer
A. HeisenbergExplanation
The statement "Position and momentum cannot be measured simultaneously" is a fundamental principle in quantum mechanics known as the Heisenberg uncertainty principle. It states that it is impossible to know both the exact position and momentum of a particle simultaneously with complete accuracy. This principle arises due to the wave-particle duality of quantum particles, where the act of measuring one property disturbs the other. Therefore, the correct answer is Heisenberg.Rate this question:
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- 11.
"The discrete energies observed, having been emitted by an alpha particle or gamma photon from a nucleus, correspond to the difference between two nuclear [...]
Correct Answer
energy levelsExplanation
The discrete energies observed are the specific energy values that are emitted by an alpha particle or gamma photon from a nucleus. These energies correspond to the difference between two nuclear energy levels. This means that when an alpha particle or gamma photon is emitted, the energy difference between two specific levels within the nucleus is released in the form of discrete energy.Rate this question:
- 12.
The Bainbridge mass spectrometer provides evidence for the existence of ...
- A.
Protons
- B.
Neutrons
- C.
Isotopes
- D.
Nuclides
Correct Answer
C. IsotopesExplanation
The Bainbridge mass spectrometer is a device used to separate and analyze isotopes based on their mass-to-charge ratio. By measuring the different masses of isotopes, the mass spectrometer provides evidence for the existence of isotopes. Isotopes are atoms of the same element that have different numbers of neutrons, resulting in different atomic masses. Therefore, the correct answer is isotopes.Rate this question:
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- 13.
The electrically neutral, virtually undetectable particle accounting for the "missing" energy in beta decay is known as a(n)
Correct Answer
neutrinoExplanation
In beta decay, a neutron is converted into a proton, and in the process, a high-energy electron (beta particle) is emitted. However, the observed energy of the beta particle is less than the total energy released in the decay, leading to the concept of "missing" energy. The explanation for this missing energy is the existence of a neutral, virtually undetectable particle called a neutrino. Neutrinos are extremely light and interact weakly with matter, making them difficult to detect. They carry away the missing energy and momentum in beta decay, ensuring the conservation of energy and momentum in the process.Rate this question:
- 14.
"Antineutrino is the antimatter form of the neutrino, and accounts for missing energy in beta minus decay"
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because antineutrino is indeed the antimatter form of the neutrino. In beta minus decay, a neutron in an atomic nucleus decays into a proton, emitting an electron and an antineutrino. This antineutrino carries away some of the energy from the decay process, which is why it is said to account for the missing energy.Rate this question:
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- 15.
A small rocky body that drifts around the Solar System is known as a(n)
Correct Answer
asteroidExplanation
A small rocky body that drifts around the Solar System is known as an asteroid. Asteroids are remnants from the early formation of the Solar System and are primarily found in the asteroid belt, a region between the orbits of Mars and Jupiter. They vary in size, with some being as small as a pebble and others being several hundred kilometers in diameter. Due to their composition and size, asteroids can pose a potential threat to Earth if they collide with our planet.Rate this question:
- 16.
The bits of the asteroids that arrive on Earth are called ...
- A.
Comets
- B.
Earth asteroids
- C.
Meteorites
- D.
Constellations
Correct Answer
C. MeteoritesExplanation
The bits of the asteroids that arrive on Earth are called meteorites. Meteorites are remnants of asteroids or other celestial bodies that survive their journey through Earth's atmosphere and land on the surface. They provide valuable insights into the composition and history of asteroids and the solar system as a whole.Rate this question:
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- 17.
Comets are mixtures of rock and ice in elliptical orbits around the sun. Their tales always point towards the sun
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Their tales always point away from the sunRate this question:
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- 18.
Any region of the sky labelled according to patterns of stars is known as a ...
Correct Answer
constellation
stellar constellationExplanation
A constellation is any region of the sky that is labeled according to patterns of stars. These patterns form recognizable shapes or figures that have been named and identified by astronomers throughout history. A stellar constellation refers specifically to a constellation that consists of stars. Therefore, both constellation and stellar constellation are correct answers to this question.Rate this question:
- 19.
Stars are grouped into so-called stellar ...
- A.
Groups
- B.
Constellations
- C.
Clusters
Correct Answer
C. ClustersExplanation
Stars are grouped into clusters, which are dense and compact groups of stars that are gravitationally bound together. These clusters can be open clusters or globular clusters. Open clusters are relatively young and contain a few hundred to a few thousand stars, while globular clusters are much older and contain hundreds of thousands to millions of stars. These clusters are important for studying stellar evolution and can provide valuable insights into the formation and dynamics of galaxies.Rate this question:
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- 20.
Very large clusters are known as "abnormal clusters"
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
They are known as "super clusters".Rate this question:
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- 21.
Our sun is stable because their is an equilibrium between outward pressure and inward [...] force
Correct Answer
gravitational
gravitationExplanation
The correct answer is gravitational. The explanation is that the stability of our sun is maintained by a balance between the outward pressure caused by the nuclear fusion reactions in its core and the inward gravitational force that tries to collapse the sun. This equilibrium between the two forces allows the sun to maintain its shape and size over long periods of time.Rate this question:
- 22.
The total power radiated by a star is called its ...
- A.
Apparent brightness
- B.
Absolute brightness
- C.
Apparent magnitude
- D.
Luminosity
Correct Answer
D. LuminosityExplanation
Luminosity refers to the total power radiated by a star. It is a measure of the star's intrinsic brightness and is independent of its distance from the observer. Apparent brightness, on the other hand, is the measure of how bright a star appears from Earth and can vary based on the star's distance. Absolute brightness is another term for luminosity, and apparent magnitude is a measure of how bright a star appears to an observer on Earth, taking into account both distance and intrinsic brightness.Rate this question:
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- 23.
"The power received per unit area by a receiver on Earth is called the absolute brightness of the star
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
"Apparent brightness" is correct.Rate this question:
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- 24.
The seven main spectral classes, in order of increasing surface temperature, are the following:
- A.
O, B, A, F, G, L, T
- B.
O, B, A, F, G, K, M
- C.
M, K, G, F, A, B, O
- D.
T, L, G, F, A, B, O
Correct Answer
C. M, K, G, F, A, B, OExplanation
The answer M, K, G, F, A, B, O represents the correct order of the seven main spectral classes in increasing surface temperature. The spectral classes are a classification system used to categorize stars based on their surface temperature. The sequence starts with the coolest stars (M) and progresses to the hottest stars (O). This order is based on the spectral features observed in the stars' spectra, with each class having its own unique set of characteristics.Rate this question:
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- 25.
Within spectral class O, the stars are the hottest. Which color do these stars have?
- A.
Blue
- B.
Yellow
- C.
White
- D.
Red
Correct Answer
A. BlueExplanation
Red - coldest. Yellow - a little hotter. White - hotter still. Blue - hottest.Rate this question:
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- 26.
Astronomers quote values of [...] in order to compare luminosities on an easy and familiar scale
Correct Answer
absolute magnitudeExplanation
Astronomers use the concept of absolute magnitude to compare the luminosities of celestial objects on a standardized scale that is easy to understand and familiar. Absolute magnitude is a measure of the intrinsic brightness of an object, independent of its distance from Earth. By using absolute magnitude, astronomers can accurately compare the true brightness of different objects, even if they are located at different distances from us. This allows for a more meaningful comparison and analysis of the luminosities of various celestial bodies.Rate this question:
- 27.
A star moving relative to the Earth will show a doppler shift in its absorption spectrum. Light from stars that are receding - red-shifted Light from stars that are approaching - blue-shifted
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
When a star is moving relative to the Earth, its light will experience a Doppler shift. This means that the wavelength of the light will change, causing a shift in the absorption spectrum. If the star is moving away from us, the light will be red-shifted, meaning the wavelengths will be stretched and shifted towards the red end of the spectrum. On the other hand, if the star is moving towards us, the light will be blue-shifted, with the wavelengths compressed and shifted towards the blue end of the spectrum. Therefore, the statement is true.Rate this question:
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- 28.
Which of the following is not a characteristic of a red giant star?
- A.
Very large
- B.
Red in color
- C.
Source of energy is fusion
- D.
Comparatively hot
Correct Answer
D. Comparatively hotExplanation
A red giant star is known for its large size, red color, and source of energy being fusion. However, it is not known for being comparatively hot. Red giants are actually cooler than main sequence stars, despite their larger size. This is because as a star expands into a red giant, its outer layers cool down while its core continues to burn, causing the overall temperature to decrease. Therefore, being comparatively hot is not a characteristic of a red giant star.Rate this question:
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- 29.
White dwarves are comparatively hot
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
White dwarves are comparatively hot because they are the remnants of low to medium mass stars that have exhausted their nuclear fuel. As these stars collapse under their own gravity, their outer layers are expelled, leaving behind a dense core composed mainly of carbon and oxygen. The core continues to radiate heat as it slowly cools down over billions of years. Despite their small size, white dwarves can have surface temperatures of tens of thousands of degrees Celsius, making them hotter than many other celestial objects.Rate this question:
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- 30.
Cepheid variables are observed to have regular variation in brightness but not in luminosity
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Variation in brightness implies there must be variation in luminosity tooRate this question:
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- 31.
Stars that are basically "two stars" orbiting around their common centre of mass are known as [...] stars
Correct Answer
binaryExplanation
Stars that are "two stars" orbiting around their common center of mass are known as binary stars. Binary star systems are quite common in the universe, where two stars are gravitationally bound to each other and revolve around a common point. These stars can have different sizes, masses, and distances from each other. The study of binary stars provides valuable information about stellar evolution, mass determination, and gravitational interactions.Rate this question:
- 32.
Which of the binary stars can be distinguished as one using a telescope?
- A.
Spectroscopic binary star
- B.
Visual binary star
- C.
Eclipsing binary star
Correct Answer
B. Visual binary starExplanation
A visual binary star can be distinguished as one using a telescope because it consists of two stars that are close enough together to be observed as a single point of light. These stars are physically bound and orbit around a common center of mass. By observing the motion of these stars over time, astronomers can determine their orbital parameters and study their properties. In contrast, spectroscopic binary stars can only be detected through changes in their spectral lines, and eclipsing binary stars can only be identified when one star passes in front of the other, causing periodic changes in brightness.Rate this question:
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- 33.
Is it the spectroscopic or the eclipsing binary star that is identified from the analysis of the spectrum of light from the star?
- A.
Spectroscopic
- B.
Eclipsing
Correct Answer
A. SpectroscopicExplanation
The correct answer is spectroscopic. Spectroscopic binary stars are identified from the analysis of the spectrum of light from the star. This analysis allows astronomers to observe the Doppler shift in the star's spectral lines, indicating the presence of two stars in orbit around each other. Eclipsing binary stars, on the other hand, are identified by the periodic dimming of the star's light as one star passes in front of the other.Rate this question:
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- 34.
Hence, the binary star identified from the analysis of the brightness of the light from it is a(n) [...] binary star
Correct Answer
eclipsingExplanation
Based on the information provided, the binary star identified from the analysis of the brightness of the light from it is an eclipsing binary star. Eclipsing binary stars are characterized by one star passing in front of the other, causing periodic changes in the observed brightness. This phenomenon occurs when the orbital plane of the binary system is aligned with the line of sight from Earth, resulting in regular eclipses. Therefore, the correct answer is "eclipsing".Rate this question:
- 35.
On a Hertzsprung-Russell diagram, what do the dots represent?
- A.
Spectral classes
- B.
Different stars
- C.
Absolute magnitude
Correct Answer
B. Different starsExplanation
On a Hertzsprung-Russell diagram, the dots represent different stars. The diagram plots the luminosity (or absolute magnitude) of stars against their surface temperature (or spectral class). Each dot on the diagram represents a star, with its position indicating its characteristics. The dots are used to show the range and distribution of stars based on their properties, allowing astronomers to study and classify different types of stars based on their position on the diagram.Rate this question:
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- 36.
The normal, stable stars can be seen along a line moving from the top left corner and then diagonically down the H-R Diagram. This "line" is known as the ...
Correct Answer
main sequenceExplanation
The main sequence is a line on the H-R Diagram that represents the majority of stars. It shows the relationship between a star's temperature and its luminosity. Normal, stable stars can be found along this line, moving from the top left corner (where the hottest and brightest stars are) diagonally down to the bottom right corner (where the coolest and dimmest stars are). The main sequence is significant because it represents the longest and most stable phase in a star's life cycle.Rate this question:
- 37.
A star with a parallax angle of one second of arc must be about 3.08 * 10^16 m away. This distance is also known as one ...
Correct Answer
parsec
pcExplanation
The correct answer is parsec (pc). A star with a parallax angle of one second of arc is about 3.08 * 10^16 m away. This distance is equivalent to one parsec, which is a unit of length used in astronomy to measure large distances.Rate this question:
- 38.
The absolute magnitude of a star is the [...] that it would have IF it were observed from a distance of 10 parsecs
Correct Answer
apparent magnitudeExplanation
The absolute magnitude of a star is the intrinsic brightness or luminosity that it would have if it were observed from a distance of 10 parsecs. This value is independent of the star's distance from Earth. On the other hand, the apparent magnitude is the brightness of a star as observed from Earth. It takes into account both the intrinsic brightness of the star and its distance from Earth. Therefore, the apparent magnitude is the correct answer as it represents the observed brightness of a star from our vantage point on Earth.Rate this question:
- 39.
What method for measuring stellar distances have a distance limit of about 10 Mpc?
- A.
Cepheid variable method
- B.
Spectroscopic parallax
- C.
Parallax method
Correct Answer
B. Spectroscopic parallaxExplanation
Cepheid variable - above 10 Mpc. Parallax method - up to 100 pcRate this question:
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- 40.
Write down the name of the guy who demonstrated a paradox to Newton's assumptions about the Universe
Correct Answer
OlberExplanation
Olber demonstrated a paradox to Newton's assumptions about the Universe. The Olber's Paradox states that if the Universe is infinite, static, and filled with an infinite number of stars, then every line of sight should eventually end on the surface of a star, making the night sky as bright as the surface of the Sun. However, this is not observed, leading to the paradox.Rate this question:
- 41.
The theoretical value of density that would create a flat universe is called the [...]
Correct Answer
critical densityExplanation
The theoretical value of density that would create a flat universe is called the critical density. This is the density at which the expansion of the universe would eventually come to a halt. If the actual density of the universe is less than the critical density, the universe would continue to expand forever. On the other hand, if the actual density is greater than the critical density, the universe would eventually collapse in on itself. The concept of critical density is crucial in understanding the fate and evolution of the universe.Rate this question:
- 42.
An open Universe is one that is brought to a stop and then collapses back on itself
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
A closed Universe is being defined. An open Universe is one that continues to expand forever.Rate this question:
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- 43.
It is believed that most matter in the Universe does not radiate sufficiently for us to detect it. This type of matter is known as ...
- A.
Cold matter
- B.
Invisible matter
- C.
Dark matter
- D.
Doesn't matter
Correct Answer
C. Dark matterExplanation
Dark matter is the correct answer because it is a type of matter that does not emit, absorb, or reflect light, making it invisible and difficult to detect. It is believed to make up a significant portion of the total matter in the universe and plays a crucial role in the formation and evolution of galaxies. Its existence is inferred through its gravitational effects on visible matter and the cosmic microwave background radiation.Rate this question:
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- 44.
Which of the following is not a theory that aims to explain why there is so much dark matter and what it consists of?
- A.
MACHO theory
- B.
NACHO theory
- C.
WIMP theory
Correct Answer
B. NACHO theoryExplanation
The NACHO theory is not a theory that aims to explain why there is so much dark matter and what it consists of. This is because the NACHO theory does not exist or is not recognized in the scientific community as a valid explanation for dark matter. The MACHO theory and WIMP theory, on the other hand, are well-known theories that attempt to explain the existence and nature of dark matter.Rate this question:
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