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PHYS295 Midsession
Midsession Exam Study
| Question | Answer |
|---|---|
| What is the main theory for how the moon was formed? | Giant Impact Hypothesis. |
| What does the Giant Impact Hypothesis say? | A collision between earth and a Mars-sized object caused the formation of the moon. |
| What evidence supports Giant Impact Hypothesis? | The Earth and moon share similar isotopic composition. |
| What are some alternative theories to the formation of the moon? | Fission Theory, Capture Theory and Co-formation by Accretion Theory. |
| What are the four main phases of the moon? | New moon, first quarter, full moon, last quarter. |
| What are the additional four phases of the moon? | Waxing crescent, waxing gibbous, waning gibbous, waning crescent. |
| How long does it take for all 8 phases of the moon to cycle through? | Approximately 29.53 days. |
| How long is a sidereal month? | Approximately 27.3 days. |
| What is a sidereal month? | How long it takes for the moon to rotate 360 degrees. |
| What is a draconic month? | How long it takes the moon to complete a full orbit around earth. |
| How long is a draconic month? | Approximately 27.21 days. |
| What is a solar eclipse? | When the moon blocks the sun's light, casting a shadow on Earth. |
| What is a lunar eclipse? | When the Earth casts a shadow on the moon. |
| When do solar and lunar eclipses occur? | When a full moon appears on a node. |
| What causes tides? | The moon's gravitational pull creating two bulges in the ocean, one close to the moon and the other on the opposite side of the Earth. |
| What is gravitational force inversely proportional to? | Distance. |
| What is reflection? | Reflection occurs when a beam of light "bounces off" an obstacle at the same angle in which it hit the obstacle. |
| What is refraction? | Refraction occurs when a beam of light passes through an obstacle and its angle changes from the angle in which it hit the obstacle. |
| What does Snell's Law state? | The angle of refraction moves towards the normal after it passes through the obstacle (line perpendicular to the obstacle). |
| What is Fermat's Principle? | The principle of least time. |
| What does Fermat's Principle state? | When light is travelling between two points, it takes the path that requires the least time. |
| What does Huygen's Principle talk about? | How the direction of light changes in refraction according to spherical wavelets that spread out at each point that the light hits the obstacle. |
| Which has smaller wavelength, blue light or red light? | Blue light. |
| What is diffraction? | The spreading of light waves as light passes through an obstacle. |
| Why is the sky blue? | Because of the way the light from the sun scatters when it reaches Earth's atmosphere. |
| Why are sunsets predominantly red? | The angle at which the light from the sun is passing through Earth's atmosphere causes changes to the scattering of the light. |
| What is the duality of light? | The concept that light acts as both a wave and a particle depending on how it is measured. |
| What is polarisation? | The restriction of light waves to a single geometric plane. |
| What is the Doppler Shift/Effect? | The change in frequency or wavelength of a light wave in relation to an observer who is moving relative to the source of light. |
| How does the Doppler Effect work? | As the observer moves away from the source of light the wavelengths lengthen, and as the observer moves towards the source of light the wavelengths shorten. |
| How do we know how much light bends towards the normal during refraction? | The shorter the wavelength, the more the light bends towards the normal. |
| What is the smoothness required for a reflecting surface directly proportional to? | The wavelength. |
| How does light scattering work? | Particles that are smaller than the wavelength of the light in question are more effective at scattering light with smaller wavelengths. |
| Where are the Maunakea Observatories located? | On the dormant volcano Mauna Kea in Hawaii. |
| Where is the Siding Springs Observatory located? | Coonabarabran, NSW. |
| Where is the Australian Telescope Compact Array located? | Narrabri, NSW. |
| What are the Maunakea Observatories used to detect? | Objects in space, with a planetary focus (e.g the atmospheres of planets, interstellar asteroids, distant exoplanets, young star clusters, distant galaxies, blackholes, and exploding stars). |
| What is the Siding Springs Observatory used to detect? | Objects in space, with a universal focus (e.g. the chemical composition of stars, the universe's age and expansion, near-Earth asteroids, bursts of gamma-rays, and galaxies in deep space). |
| What is the Australian Telescope Compact Array used to detect? | Objects in space, with a focus on the light spectrum (e.g. radio waves left behind by exploding stars, radio-emitting jets from blackholes, the formation of stars, chemical molecules floating in space, invisible magnetic fields, and gamma-ray flares). |
| What is the area of the aperture directly proportional to? | Light gathering power. |
| What is the aperture diameter directly proportional to? | Resolution. |
| What is the image size directly proportional to? | Focal length. |
| Why is refraction useful in telescopes? | Refraction allows the magnification of objects into a focal plane. |
| What is the difference between a shorter and longer focal length? | A shorter focal length creates a smaller and brighter image, a longer focal length creates a larger and fainter image. |
| What powers the sun? | Nuclear fusion. |
| What is nuclear fusion? | A reaction where two or more atomic nuclei "fuse" to form a heavier nucleus, causing a huge release of energy. |
| What is the sun made up of? | Plasma - specifically very hot hydrogen and helium. |
| Does the sun's core consist of more helium or hydrogen? | Hydrogen. |
| Why has the sun's core composition changed over time? | Due to the nuclear fusion of hydrogen into helium. |
| What are sunspots? | Dark spots on the sun's surface that appear cooler than their surroundings. |
| What causes sunspots? | The convective flow of heat from the sun's interior to its surface due to an intense magnetic field. |
| How much stronger is the magnetic field that causes sunspots than Earth's magnetic field? | About 3000 times stronger. |
| What is the period between sunspot maximas? | About 11 years. |
| What does Kepler's 3rd Law state? | The orbital time T and orbital radius r are related by T^2 being directly proportional to r^3. |
| What does Kepler's 1st Law state? | Planets orbit the sun in an ellipse with the sun at one focus. |
| What does Kepler's 2nd Law state? | A line joining planets to the sun sweep out equal areas in equal intervals of time. |
| What does Kant's Nebular Hypothesis 101 state? | The solar system was formed by a giant cloud of rotating gas and dust which collapsed due to gravity, forming the sun, planets and other things. |
| What is a moon day? | The amount of time it takes for the moon to orbit the Earth in one full rotation. |
| What is the fun fact about height and the moon? | You are taller under a full moon! |
| Is Mercury a gassy or rocky planet? | Rocky planet. |
| Is there water on Mercury? What evidence backs this up? | We believe there is water on Mercury due to photographed shadows in craters suggesting frozen water exists. |
| What is Mercury's core made up of? | Iron. |
| What is Mercury's atmosphere made up of? | Hydrogen, Helium, Oxygen, Sodium, Potassium, and Argon. |
| What does the global temperature on a planet depend on? | Distance from the sun. |
| Is Venus a gassy or rocky planet? | Rocky planet. |
| Why is Venus hotter than Mercury? | The Greenhouse Effect. |
| How young is Venus' surface? | Less than 800 million years old. |
| What is Venus' atmosphere made up of? | Carbon Dioxide, Nitrogen, Argon, and water. |
| What is Earth's atmosphere made up of? | Nitrogen, Oxygen, water, Argon, and Carbon Dioxide. |
| Is Mars a gassy or rocky planet. | Rocky planet. |
| Is there water on Mars? What evidence backs this up? | Mars at least used to have water. We know this because of meandering canyons, dendritic channels and lobate craters. |
| What is Mars' atmosphere made up of? | Carbon Dioxide, Nitrogen, Argon, and water. |
| Is Jupiter a gassy or rocky planet? | Gassy planet - specifically a Gas Giant. |
| Is Saturn a gassy or rocky planet? | Gassy planet - specifically a Gas Giant. |
| Is Uranus a gassy or rocky planet? | Gassy planet - specifically an Ice Giant. |
| Is Neptune a gassy or rocky planet? | Gassy planet - specifically an Ice Giant. |
| What are the atmospheres of Jupiter, Saturn, Uranus and Neptune made up of? | Hydrogen, Helium, Methane, Ammonia, and Hydrogen Sulfide |
| Name the planets in our solar system. | Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. |
| When was Pluto demoted to Dwarf planet status? | August, 2006. |
| What is the name of Neptune's biggest moon? | Triton. |
| What is a key feature on Neptune's moon Triton? | The geysers/"icy volcanos". |
| What is the name of Saturn's biggest moon? | Titan. |
| Which planet has the most moons? How many moons? | Saturn with 293 moons. |
| Which planet has the most volcanoes? How many volcanoes? | Venus with over 1600 major volcanoes. |
| What is chromatic abberation? | When a telescope lens fails to focus all colours of light at the same single point. |
| What is the definition of a planet? | A planet must: (a) orbit the sun, (b) have enough mass and gravity to pull itself into an almost round shape, and (c) have strong enough gravity to clear its orbit of small objects. |
| What are absorption spectra? | They show dark missing lines on a continuous rainbow background when light passes through a cool gas. |
| What are emission spectra? | They show bright coloured lines on a dark background when hot gas emits light. |
| What is the hydrostatic equillibrium? | A property of the sun, which involves the inward pull of gravity from the nuclear fusion in the core being perfectly balanced with the outward gravitation pull (so the sun doesn't implode or explode). |
| What is Coulomb Force? | The attraction or repulsion between two charged particles. |
| What does Kirchoff's First Spectral Law state about a continous spectrum? | A hot, dense gas produces a continuous light spectrum. |
| What does Kirchoff's Second Spectral Law state about an emission line spectrum? | A hot, transparent gas produces an emission line spectrum, appearing as bright coloured lines on a dark background. |
| What does Kirchoff's Third Spectral Law state about an absorption line spectrum? | A cool, transparent gas produces an absorption line spectrum, appearing as dark missing lines along a continuous rainbow background. |
| What is an exo-planet? | A planet that orbits a host star that is not our Sun. |
| What is the habitable zone? | The distance from a host star where a planet could maintain water (and thus possibly life) on its surface. |
| What are the two most commonly used methods to detect exo-planets? | Astrometric and Radio Velocity Technique. |
| What are the three main sources of ionising radiation in space? | Galactic Cosmic rays, Solar Particle Events, and trapped particles |
| What health effect can exposure to ionising radiation in space have? | Nausea and vomiting, central nervous system damage, risk of cancer, diseases in the central nervous and cardiovascular system, and death. |
| How/why does ionising radiation effect our health? | Ionising radiation interacts with our DNA, and can break apart and damage our DNA, causing various health impacts. |
Created by:
Knerdy
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