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Physics EOY Rev
Light & colour, Density & Pressure and Astrophysics
Question | Answer |
---|---|
Use SOURCE in a sentence | a source emits light |
Use REFLECT in a sentence | light is reflected off a mirror |
Use TRANSMIT in a sentence | light is transmitted through glass |
Meaning of LUMINOUS | something that reflects light |
Meaning of NON-LUMINOUS | something that does not give off light |
Meaning of TRANSLUCENT | an object which allows partial transmission of light through |
Meaning of OPAQUE | no light can be transmitted through |
What is the SPEED OF LIGHT in a vacuum | 300,000,000 m/s |
What is the order of the ELECTROMAGNETIC SPECTRUM | Rabbits, Mate, In, Very, Unusual, Xpensive, Gardens Radiowaves, Microwaves, Infrared, Visible, Ultraviolet, X-ray, Gamma Rays |
Which EM waves have the highest FREQUENCY? | Gamma Rays |
Which EM waves have the longest WAVELENGTHS? | Radiowaves |
What is the equation for working out calculations of light time? | Distance = Speed x Time |
Draw an image to locate the image formed by a plane mirror | DRAW |
What is SPECULAR reflection? | . When light rays are reflected off smooth surfaces. . It creates a clear image |
What is DIFFUSE scattering? | . When light rays are reflected off of an irregular surface . It scatters the light and creates a distorted image |
Draw examples of Specular Reflection and Diffuse Scattering | DRAW |
What are the LAWS OF REFLECTION? | 1. Angle of incidence = angle of reflection 2. Virtual image is the same shape, size, colour and distance from mirror as the object, just reversed |
Draw an accurate ray diagrams of reflection | DRAW |
How would you test the LAWS OF REFLECTION | 1. Draw a straight line on a piece of paper 2. Draw another line perpendicular to it (the normal) 3. Place a mirror along the first line 4. Place a ray box about 20 degrees from the normal 5. Measure if incidence and reflection are the same |
What happens when light is REFRACTED? | . It is the bending of light . When light is moving between mediums of different densities . In higher densities it moves slower and faster in lower densities |
Draw a diagram of light being refracted through a variety of different mediums | DRAW |
What is APPARENT DEPTH? | . When something in water appears shallower than reality . The light is refracted at the surface of the water and bends away from the water . Human eyes assume light will travel in a straight line and see an 'apparent' image above the real object. |
Draw a diagram of a human seeing an apparent image of a fish in the water | DRAW |
What is TOTAL INTERNAL REFLECTION | .When a light ray reflects at the boundary between two mediums . It can be between a less dense and a more dense medium |
When does TOTAL INTERNAL REFLECTION happen? | When the incident angle at the boundary of a medium is higher than the specific Critical Angle of the two mediums. |
When will light be at the CRITICAL ANGLE | When the incident angle at the boundary of a medium is equal to the Critical Angle of the medium makes the light go along the boundary between the two mediums (90 degrees) |
Draw ray diagrams of TIR in prisms | DRAW |
When is TIR used in real life? | . In optical fibres - light rays are totally internally reflected many times within it: Endoscopes and computer communications in nearby areas. |
What is WHITE LIGHT made up of? | All visible colours of light |
How is white light dispersed into its component colours? | Passing it through a suitably shaped prism |
What are the three primary colours of light | Red, Blue, and green |
What are the secondary colours of light? | r+g= YELLOW r+b= MAGENTA b+g= CYAN |
WWhat will happen to colours in a coloured filter? | a coloured filter will transmit and reflect its own colour and absorb others |
What colour will YELLOW be in RED light? | Red |
hat colour will MAGENTA be in CYAN light? | Blue |
What colours does apple reflect and absorb? | The leaf reflects green and absorb ROYBIV The apple reflects red and absorbs OYGBIV |
What happens to black and white colours? | black objects absorb all visible colours of light; white objects reflect all colours of light |
What is the equation for finding DENSITY of objects? | Density = MASS /VOLUME |
What are density's units of measure? | kg/m3 --- x1,000,000,000--- g/cm3 |
How do you find the density of a regular shape? | 1. Measure the height, width, depth and multiply (Volume) 2. Weigh the object (Mass) 3. Divide the weight (in grams) by the volume (in cm3) = g/cm3 |
How do you find the density of an irregular shape? | 1. Weigh the object 2. Use a eureka can to find the displaced volume 3. divide mass by volume = g/cm3 |
How do you find the density of a liquid? | 1. weigh an empty container 2. Weigh the container with the liquid inside 3. take away the first weight from the second weight (mass) 4. Use a measuring cylinder to measure ml of liquid (volume) 5. Divide the mass in g by the volume in cm3 = g/cm3 |
What is the equation for finding PRESSURE in objects? | Pressure = FORCE / AREA |
What are pressure's units of measure? | N/cm2 --- x10,000--- Pascals N/cm2 --- x10,000--- N/m2 |
When is there higher pressure? | When there is less surface area, there is more pressure because all the force is concentrated in one point. When there is more surface area, there is less pressure because all the force is spread out evenly across the surface. |
When are examples of when you need to use high pressure? | When using a knife- it needs a slim blade with smaller surface area and high pressure for easy cuts |
When are examples of when you need to use low pressure? | With skis- it has a large surface area and low pressure so that the skier does not sink. |
How does adding more particles to a container of gas change the pressure? | It increases the likelihood of particle collisions and therefore increases pressure |
How does heating the container change the pressure? | It increases pressure because the kinetic energy increases and speeds up, having more collisions |
How does reducing the volume of the container change the pressure? | The container doesn't have much space between the walls, increasing collisions |
What are the main classes of naked- eye objects? | Sun, Moon, Planet, Comets, Meteors |
Give a description about the sun | - Centre of our solar system - Largest thing in solar system - It has a gravitational field which makes the planets orbit it |
Give a description about the Moon | - The natural satellite orbiting earth |
Give a description about Planets | - celestial bodies orbiting a star - must have enough gravity to be forced into a spherical shape - cleared neighbourhood |
Give a description about Comets | - Large objects of dust and ice - Elliptically orbit the sun - Smaller than planets |
Give a description about Meteors | - a large rock that has entered the Earth's atmosphere - Boiling hot due to friction - Appear as streaks of light |
What is a natural satellite | things like moons that orbit planets |
What are artificial satellites | manmade devices for scientific discovery |
Name the order of the Planets from the Sun | Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune |
Which planets are Inner (terrestrial) planets | Mercury, Venus, Earth, Mars |
Which planets are outer planets (gas giants) | Jupiter, Saturn, Uranus, Neptune |
Where is the Asteroid Belt | It is between the terrestrial planets and teh gas giants |
What is the Asteroid belt made up of | Debris, dust, rock and metal |
What is the Kuiper Belt? | - A large region in the outer solar system where icy objects, comets and dwarf planets orbit the sun - Bigger and wider than the asteroid belt |
What is the Oort cloud? | - contains billions of frozen comet-like bodies that form a gigantic ball shaped place surrounding our solar system - Objects here are composed of water, ice, ammonia and methane |
What is a galaxy? | A gravitationally bound group of billions of stars |
What is the closest galaxy to the Milky Way | Andromeda Galaxy |
What is the role of gravity in our solar system | . Gravity pulls planets and moons into orbit around a star . It shapes the planets into spherical shapes |
What is the difference between mass and weight | . Mass is the amount of matter in the object (kg) . Weight is force of gravity on the object pushing it down (N) |
what is the equation for finding out the WEIGHT of an object | weight= mass x gravitational field strength |
what is NEWTON'S CANNON | It is a scientifical way of explaining orbits. It states that if a cannon ball was shot from a high mountain, if it had just the right amount of velocity, the fall would match the curvature of the Earth and would go into orbit. |
What is the equation for finding out ORBITAL SPEED | (2 x π x orbital radius) / orbital time period |
What is the origin of DAY and NIGHT? | . Earth spins on its axis: a full round takes 24 hours . Day occurs in a country when it is facing the sun . Night occurs when the country is facing away from the sun |
What is the origin of SEASONS? | . Seasons occur due to the tilt of the Earth's surface . Winter: the hemisphere experiencing it is tilted away from sun . Summer: hemisphere experiencing it is titled towards the sun |
What does the NEW MOON look like? | Nothing is visible |
What does a WAXING CRESCENT look like? | Less than half of the moon is visible The right side is the visible side |
What does a WAXING HALF MOON look like? | Half of the moon is visible The right side is visible |
What does a WAXING GIBBOUS look like? | More than half of the moon is visible Majority of right side is visible |
What does a FULL MOON look like? | Whole moon is visible |
What does a WAXING GIBBOUS look like? | More than half of the moon is visible Majority of the right side is visible |
What does a WANING HALF MOON look like? | Half of the moon is visible Left side is visible |
What does a WANING CRESCENT look like? | Less than half of the moon is visible The left side is the visible side |
What is the moon's ORBITAL PERIOD? | 28 days |
What is the moon's SPIN PERIOD? | 28 days - we only see one side of the moon |
Why do the Moon and Sun look the same size from Earth? | Because their distances are proportionate to their sizes. |
What is a Lunar Eclipse? | When the Earth blocks sunlight from lighting up the moon |
What is a Solar Eclipse? | When the moon block sunlight from reaching the Earth It creates an umbra (shadow) and usually a penumbra (half eclipse) |
What is the age of the Universe? | 13.8 billion years |
How old is the Earth? | 4.5 billion years |
What is the origin of the Universe | The Big Bang Theory - the universe it still expanding since then |