Seeing the Light

Seeing the Light – Topic 1 Science Revision

Objects may be luminous or non-luminous (ie. Emits its own light)

Some definitions:

Aperture: Hole or opening that controls the amount of light which is admitted

Beam: Wide stream of light rays traveling in the same direction

Concave: An inward curving surface

Cones: Cells located in the retina that respond to either red, green or blue light

Converge: Light rays moving towards each other

Convex: And outward curving surface

Dispersion: The separation of colours that make up white light

Diverge: Light rays moving so that they spread out

Focal Point: The point where light rays meet after passing through a lens

Opaque: Describes a substance that does not allow any light to pass through (brick wall)

Ray: Narrow beams that trace the path of light

Reflection: Where light bounces off a surface

Refraction: The changing in speed and thus direction of light as it passes into different media

Rods: Cells located in the retina that respond to the brightness of light, they are responsible for peripheral and night vision

Scattering: Where light is sent in many directions

Translucent: Describes a substance that allows some light to pass through meaning shapes can be seen but with little clarity (frosted glass)

Transparent: Describes a substance that allows most light to pass through meaning objects can be seen clearly (window)

Virtual focus: The common point from where light rays appear to originate, ie. a focus that does not exist but is imagined or assumed by continuing light paths


The Moon
-Phases of the moon change on a 29.5 day cycle
-Caused by relative position of sun, moon and earth
-Half the moon is ALWAYS lit by the sun
-Light always travels in straight lines, so the moon may block the sun (lunar eclipse)
-The sun, moon and earth are on different planes
Phases:



Light Refraction

-Observations: Images in the water at an angle appear magnified and bent
-Apparent position is above the actual position
-Refraction occurs when light travels between media
-Slows down, wavelength changes
-Light through air: 3x108 m/s (300 000 000)
-Light through water: 2x108 m/s (200 000 000)
-Light through glass: 2.25x108 m/s (225 000 000)
-Directional change as it enters the second medium
-When approaching at a perpendicular angle, refraction does not occur
-Refracted light reaches the eye as if it were approaching from a different angle
-After reaching the eye, light is traced back as a straight line
-Traced lines will have a focus different from where the actual ray originates
-Light bends towards the normal as it slows, and away as it quickens
-Angle varies as prism is turned, closer/further to normal means less/more refraction





Pinhole Camera
-The image shown will be upside down, as rays travel through the pinhole and to a point on the opposite face
-When the camera is moved toward the object, image will be larger and blurrier
-When the camera is moved away from the object, image will be smaller but sharper
-A bigger pinhole will produce brighter but blurrier images because more light is able to enter
-A smaller pinhole will produce sharper but duller images
Mirrors and lenses
Always measure the angle from the ray to the normal
The focal length is measured from the middle of the lens to the focal point
-The angle of incidence is equal to the angle of reflection on a plane mirror
-Biconvex Lens: converges light
-Thicker biconvex lens: focal length will be shorter because the curve is at a greater angle
-Biconcave Lens: diverges light (virtual focus)
-Concave mirror: reflects and converges light
-Convex mirror: reflects and diverges light (virtual focus)





A: Biconvex lens
B: Biconcave lens
C: Triangular Perspex
D: Rectangular Perspex


The Eye
The eye works a bit like the pinhole camera; the image will be upside down and instead of a pinhole there is the pupil



Cornea: Transparent front part of the eye connecting to the sclera through which light enters. Light is refracted here, but not as much as the lens

Sclera: The hard, flexible outer layer of the eye which is attached to tendons

Iris: The coloured part of the eye, it contracts and expands to control the amount of light entering the eye.

Muscle for movement: Controls eye movement

Vitreous Humour: Jelly-like substance that fills the space betwen the lens and the retina, helps to maintain eye shape

Lens: Biconvex structure that refracts light so that it focuses on the retina. Its shape can be changed by the ciliary muscle.

Aqueous Humour: Watery substance filling the space between the lens and the cornea

Suspensory ligament: Holds the lens in place, is directly attached to the lens

Ciliary muscles: Changes the shape of the lens in order to accommodate distances to an object. It contracts to round the lens for close work, and relaxes to flatten the lens for longer distances. It is connected to the suspensory ligament.

Retina: Sensory tissue lining the back of the eye containing photoreceptors (cone and rod cells) that capture light rays and convert them into electrical impulses. Looks like a thin, murky grey to pink film.

Choroid: The layer between the retina and the sclera that contains blood vessels and connective tissue

Blind Spot: This is the location where the retina joins to the optic nerve, meaning there are no photoreceptors in the area. When an image is at this certain position, it cannot be seen.

Optic Nerve: Transport messages from the photoreceptors to the brain

Pupil: Hole in the centre of the eye through which light passes, its size is controlled by the iris



Destinations for a light ray:
1. Outer Eye
2. Cornea
3. Aqueous Humour
4. Iris and pupil
5. Lens
6. Retina
7. Choroid via optic nerve
8. Sclera via optic nerve
9. Optic nerve
10. Brain

Seeing Colour
Cone cells are responsible for colour.
-Sensitive to red, green and blue
-These are the primary colours of light; they cannot be made by mixing other colours
-Note: They are not the same as paint
-Cone cells concentrated in the middle of the retina, with fewer on the periphery
-White light contains all colours
-When white light hits an object, all colours are absorbed except the colour that it appears to be which is reflected allowing us to see it
-We see a wide range of colours because different combinations and amounts mix to create various colours and shades.
Colours Combined Colour observed
Red + green + blue White
Red + green Yellow
Red + blue Magenta
Green + blue Cyan
Yellow + magenta + cyan White
*The secondary colours of light are magenta, cyan and yellow. They form when the primary colours overlap

Weather Revision

Weather Revision
-Weather elements: These are things you might be told to expect on a weather report
e.g. Rain, hail, sun, cloud, wind, snow, fog, mist, haze, gale, frost

Sun and Seasons

-All weather results from the troposphere, layer from 0-16km altitude
-Source of energy, wind blowing and temperatures, is the sun
-Solar energy is not evenly distributed
-Material, colour and elevation also affect energy storage and release, changing weather and climate



-Equinox is equal number of day and night hours (spring and autumn)
-Solstice is when there are the longest or shortest daylight hours (summer and winter)
-Latitude at equator is at 0 degrees
-Latitude at poles is 90 degrees
-Higher latitude = less solar energy

Air masses
-An air mass is a body of air with similar temperature and moisture levels, which influence the weather of areas it travels through
-Continental air masses have travelled over land
-Maritime air masses have travelled over oceans
-Warm air can hold more moisture than cold air
Tropical: Hot, originating in or near the tropics
Polar: Cold, Origination from or near the poles
Maritime: Moist, origination over an ocean
Continental: Dry, originating over land
Equatorial: Influences northern Aus in summer
Tropical Maritime: Warm and moist, Very warm and moist, influences Pacific/Indian ocean coasts summer thunderstorms to SA and Vic, and heavy rain along east coast
Tropical continental: Hot and dry, hot, dusty conditions in southern Aus
Southern Maritime: Cool and moist, common in southern Aus all year
Polar maritime: Cold and moist, coldest winter weather and >800m snow in SE Aus occasionally
-Southern Maritime has the greatest influence on Vic




Air Pressure
-The force exerted by the weight of air particles
-Rising and falling air pressure generates wind, cloud, cold, wet, fine, and sunny conditions
-Climate is about long term record, trends and averages; weather is the day to day experience
-Regions of sinking air = highs, high pressure regions, anticyclones
-Regions of rising air = lows, low pressure regions, depressions, cyclones
-Isobar = line used on weather maps which pass through areas with the same air pressure
-Air pressure measured in hectopascals (hPa)
High pressure:
-value of isobars increase toward centre
-air expands
-air is sinking
-air becomes warm and stable
-air spirals outwards
-in a anticlockwise direction
-cover a greater area
-move more slowly
-causes dry, cloud-free weather
Low pressure:
-value of isobars decrease toward centre
-air contracts
-air is rising
-air spirals inwards
-air cools to form clouds
-in a clockwise direction
-cover less area
-mover more quickly
-causes rain showers and cloudy weather
-Cold fronts represent line where col polar air meets warm tropical air
-Temperature difference creates strong winds (air moving to spread/even out)
-Cold air pushes warm air up
-Rising warm air can produce clouds
-71% of the Earth’s surface is water

Clouds
-a cloud is a swirling mass of water vapour
Type Level Appearance Precipitation
Cirrus High high level, white tufts or filaments; made up of ice crystals. No precipitation
Cirrocumulus High small rippled elements; ice crystals No precipitation
Cirrostratus High transparent sheet or veil, halo phenomena; ice crystals No precipitation
Altocumulus Middle layered cloud, rippled elements, generally white with some shading. May produce light showers
Altostratus Middle grey sheet, thinner layer allows sun to appear as through ground glass. Rain or snow
Nimbostratus Low thicker, darker and lower based sheet. Heavier intensity rain or snow
Stratocumulus Low layered cloud, series of rounded rolls, generally white. Drizzle
Stratus Low mass, grey, uniform base; if ragged, referred to as "fractostratus". Drizzle
Cumulus Low individual cells, vertical rolls or towers, flat base. Showers of rain or snow
Cumulonimbus Low-High very large cauliflower-shaped towers to 16 km high, often "anvil tops". Phenomena: thunderstorms, lightning, squalls. Showers of rain or snow
-Cirrus = curl of hair = wispy, high altitude
-Alto = middle = mid-altitude
-Nimbus = rain = raincloud
-Stratus = layer = sheet-like
-Cumulus = heap = puffy clouds
-Cumulonimbus = thunderclouds (summer storms etc)
Weather maps/Synoptic charts
-Summarises the state of the atmosphere at a particular period of time
-Air pressure measured at selected locations
-Isobars are drawn at 2 hectopascal intervals
-Isobars connect places with equal air pressure
e.g. ------- 126 --------
-When looking for pressure of an area, look for nearby pressure systems which enclose the area
-cool air descends to create high pressure, and cannot rise due to pressure of descending air from above, nor descend any further. So, it flows along the earth’s surface as wind and travels toward a low pressure system to replace heated rising air
-Rotation of earth drags wind of a straight line course
-Closer the isobars, stronger the wind
-Winds named after direction from which they blow, i.e. southerly wind head north
-Wind direction shown by symbol
-Barbs on tail of symbol indicate speed
-areas with rain in the last 24hrs are shaded in parallel diagonal lines
-lows and fronts associated with rising, cooling air
-produces showers or rain
-highs associated with sinking, warming air which retains moisture
-skies generally clearer, fine weather
-winds blowing off the sea often bring rain
-winds blowing from central Aus usually bring dry conditions
Determining temperatures
-After a cold front passes, temperature falls
-Southerly winds bring colder weather
-Winds from the north bring warmer weather
-Graph may be used

Glossary
Weather: The atmospheric condition for a brief period of time; the day to day experience
Climate: The atmospheric condition for a long period of time, approximately 30 years. It is a synthesis of all weather over time and is based on records, trends and averages
Air pressure: The force exerted by tiny air particles, the rises and falls of which generate weather conditions
High pressure: regions of sinking air which spirals outwards in an anticlockwise direction. High pressure is associated with dry, cloud-free weather
Low pressure: Region of rising air which spirals inwards in a clockwise direction. Low pressure is associated with rain and showers
Isobars: The lines on a weather map which pass through areas of equal pressure
Cold front: represents the line where cold polar air moving toward the equator meets warm tropical air moving pole ward
Relief (Orographic) rainfall:
1. Warm moist air cools as it is forced to rise by mountains and hills
2. Cool air condensed to form clouds
3. Precipitation falls
4. Drier air warms up as it descends the mountain/hill, producing less rain, known as a rain shadow

Convectional rainfall:
1. Air is warmed by the sun
2. Warm air expands as it rises
3. Cooler air condenses, forms clouds
4. Heavy rain is produced and falls

Frontal rainfall:
1. Cool, denser air of a low pressure system moves across earth’s surface
2. Warm, lighter air is forced to rise as the cold front moves in
3. Air is cooled, condenses, and can cause rain to fall

Invertebrate Revision

Invertebrates Revision
Invertebrate: Animal without a backbone

Phylum
Annelids (little rings)
-most in water, some in soil
-segmented worms
-soft-bodies
-take in air through moist skin
e.g. leech, earthworm, fanworm, ragworm

Arthropods (jointed foot)
-found in land and water
-segmented bodies
-exoskeleton
-paired and jointed legs
-most have antennae and compound eyes
-on land, breathing through spiracles (tubes)
-in water, breathing through gills
e.g. ants, crayfish, scorpion, spiders, crabs, flies, butterflies, millipedes, damselflies

Cnidarians (stinging cells)
-most live in the sea, several in fresh water
-soft, hollow bodies
-only one body opening
-tentacles with stinging cells
-no body organs such as heart and lungs
e.g coral, sea anemone, hydra, bluebottle, jellyfish

Echinoderms (spiny skin)
-found only in the sea
-spiny skin
-arms that radiate from centre of body, based on five parts
-tube feet for movement
-mouth and anus
e.g. brittle-star, sea urchin, starfish, sea cucumber

Platyhelminthes (flat worms)
-flat body
-unsegmented
-head-like region
-mouth opening but no anus
e.g. tapeworm, fluke, planarian, flatworm

Poriferans (bearing/with pores)
-found in water
-sponge body with many holes
-food and water enter through tiny holes in body
-waste goes through single large opening
-usually fixed in one place to rocks/shells
-skeleton of glassy/chalky needles or spongy fibres
e.g. bath sponges, glass sponges (all sponges)

Molluscs (soft body)
-Soft, unsegmented bodies
-usually covered with a protective shell
-head with eyes and/or tentacles
-mouth and anus
-muscular foot for movement
e.g. snail, slug, octopus, limpet, clam, squid, oyster

Nematodes (thread form)
-round worms
-found in water, soil, plants and animals
-worm-like body with no segments
-mouth and anus
e.g. threadworm, pinworm, hookworm, whipworm, lungworm

Arthropods
-There are more arthropods than any other animal types on earth
-All have external skeletons
-All have jointed body
-All have paired and jointed legs
-5 Arthropod groups:
1. Crustaceans – at least 10 legs, more than 3 body segments, 2 pair of antennae
(Crabs, shrimps, lobsters, prawns)
2. Arachnids – 8 legs, 2 body segments, 1 pair of antennae (very small)
(spiders, scorpions, ticks, mites)
3. Insects – 6 legs, 3 body segments, 1pair antennae
(butterflies, damselflies, bees, beetles, crickets, ladybirds)
4. Millipedes (diplopods) – 2 pairs of legs per segment, many segments, 1 pair antennae
5. Centipedes (chilopods) – 1 pair legs per segment, many segments, 1 pair antennae
Note: Together, millipedes and centipedes are myriapods
-There are 3 ways to classify arthropods
1. Number of legs
2. Number of antennae
3. Number of body segments

Insects
Insect Body Structure:
-Divided into 3 parts – head, thorax, abdomen
-Head = antennae, eyes, mouthparts
-Antennae, contain organs for smell and touch:
-Long and thin for touch (distance between predator/prey)
-Feathery antennae for sensitivity help pick up scents (e.g. of females)
-Have compound eyes:
-good for seeing movement, escape from predators
-housefly processes 100 images per second to help flying
-Mouths shaped depending on food and eating method
-Sap-sucking = tiny head, pointed tube
-proboscis is a long tubular structure, unrolls to reach nectar (hawk moth, butterfly)
-Sharp proboscis= piercing/sucking blood (female mosquitoes, bedbugs – barbed structure for piercing and sawing, feed before dawn >13 degrees, may take 5mins or more to extract blood meal)
-Also inject saliva containing substance that stops blood clotting
-Proboscis can be blown up (butterfly) or uncoiled using muscles (hawk moth)
-Proboscis is kept coiled at rest, and uncoiled for feeding
-Plant/wood-eating = large head, strong muscles/jaws to bite through plant tissue (grasshoppers and cockroaches have hard, sharp, chewing jaws
-Houseflies and bees lick up their food
-For all insects, mouth connects to digestive system
-Thorax = where legs and wings attach
-These are hollow with exoskeleton like main body
-All have 6 Legs
-Often spurs with sharp claws
-Strong limbs for grasping/holding prey
-Strong hind leg for jumping (grasshoppers)
- Wings important for classification:
-may be one or two pairs (2 or 4)
-may be covered with hairs, scales, have long silky fringes
-In beetle, front pair is hard and thick to protect flying wings when not in use (allows digging)
-Long narrow wings with fringes for fast, accurate flight
-Front and back pairs of wings joined by hooks to beat in unison
-Abdomen = number of segments
-At the end are reproductive organs:
-female = often includes long ovipositor (long thin tube for placing eggs)
-e.g. female wasps lay eggs in paralysed spiders/caterpillars, damselflies within plants
-Sting also located near end of abdomen
-exoskeleton of insects made of substance called chitin
-Tough, waterproof, springy
-Insects have no lungs
-Use trachea, fine tubes, between segments of exoskeleton to transport oxygen around body
-hearing organ location depend on insect, mosquito= base of antennae, cricket=front legs, butterfly=on thorax, cicada=abdomen



Insect Life-cycles

-In all insects: males produce sperm and transfer to female when mating, eggs fertilized, eggs laid near food supply
-Three options after this
1. No change or no metamorphosis
-When born, it already looks like adult, only smaller
-moults exoskeleton several times to allow room for growth
-e.g. silverfish
2. Part change or incomplete metamorphosis
-Young look like adults, but with no wings, different colour and shape
-they moult, grow, and gradually develop these
- stages are egg --> nymph --> adult
e.g. green vegetable bug, dragonfly, damselfly, grasshoppers, termites
3. Complete change or complete metamorphosis
-Four growth stages in their life cycle, e.g. the butterfly, flies, beetles, wasps, bees, ants
-female butterfly lays eggs on leaf (milkweed or swan plant)
-eggs hatch into tiny larva or caterpillar, monarch butterfly caterpillars are green and white
striped. Grow to 3cm long over a few weeks
-the caterpillar hangs by its ‘tail’ from a twig, and changes to pupa form (takes a few hours)
Case of monarch butterfly pupa is glossy green with gold spots.
-most of caterpillar body dissolves, reforms to butterfly
-internal and external differences
-case splits down the side, and the adult emerges
-stages are egg --> larva(caterpillar) --> pupa --> adult

Dichotomous Keys

-Have 2 options at each level
-When making one, the options are never the name of any category/animal
-when reading them, note down each option that lies on the path to a category/animal



Food webs and chains

-Show 2 main things: Feeding relationships and flow of energy
-Carnivore: Animal that eats other animals only
-Herbivore: Animal that eats plants only (primary consumer)
-Omnivore: Animal that eats plants and animals
-food --> consumer
-sun is the source of energy, start of all food chains
-plant = producer
-consumers come after the plants
-first order/primary consumer
-second order/secondary consumer (usually carnivore)
-third order/ tertiary consumer (usually carnivore)
-top order consumer (not eaten by any other animal on the chain)
-in food webs, plants go on the bottom and the consumers generally go in order upward, with the top order animals on top
- When considering the effects of changes, think about
-increase/decrease in predators
-increase/decrease in prey
-maintaining/disrupting balance of food
-main food sources
-increase/decrease in producers
-Remember that food chains often do not develop past three consumer levels, as energy is lost at each level. There would have to be huge amounts of lower consumers/producers to sustain a higher order consumer.

Carbon – CO2

-Plants take in carbon from atmosphere through leaves
-Carbon returned to atmosphere through respiration, decomposition, combustion
-Respiration takes place in every cell of the body
-Animals obtain carbon by consuming plants
-Burning of fossil fuels disrupt natural balance of carbon
-Skeletal remains of aquatic creatures, such as shells and bones, is the source of carbon in limestone
-limestone=calcium carbonate=CaCO3

ihearthorses

(tell me if there's anything else on the test that I have missed!)

Hi everyone!
Test time again, but we need to take this opportunity, AND GET PIZZA (OR PASTA)
So this is revision for our music test:

Notes of the Treble and Bass clefs:





Or rather this is the grand staff



Intervals:
-Remember to count where the note already is
-Minor thirds will sound sad
-Major thirds should sound happy
-Major thirds are the first two notes of the major arpeggio



Key Signatures:
C major – no sharps or flats
A minor – no sharps or flats, raise 7th note
G major – 1 sharp, F sharp
E minor – 1 sharp, F sharp, raise 7th note
F major – 1 flat, B flat
D minor – 1 flat, B flat, raise 7th note
Remember to raise the 7th note of minor scales!

It is likely that the test will ask us to write scales, remember to consider the:
-Clef (Treble or Bass)
-Type of note (whole half, crotchet, minum etc)
-Key signature or accidentals
-Whether the stem of the note goes up or down (down until c1)

Italian Terms:

Tempo/Speed from slowest to fastest:
Lento: very slow
Adagio: slow
Adante: at a walking pace
Moderato: moderate, interpreted by performer
Allegro: fast and lively
Presto: very fast

Dynamics from softest to loudest:
Pianissimo: very softly - pp
Piano: softly - p
Mezzo Piano: moderately softly - mp
Forte: loudly - f
Mezzo Forte: moderately loudly - mf
Fortissimo: very loud - ff
Crescendo: gradually getting louder (<)
Decrescendo/Diminuendo: gradually get softer (>)

Technique:
Staccato: short and detatched
Legato - smoothly and connected
Slur/phrase mark - without breaking it apart, connected

Instruments: be able to recognise a
Flute - http://www.youtube.com/watch?v=LI3wIHFQkAk (clear, high range, airy sound)
Oboe - http://www.youtube.com/watch?v=iSsFUQs89T0 (shrill, high range, sharp sound)
Bassoon - http://www.youtube.com/watch?v=sdrTKYDgISQ (hear vibrations, lowest range)
Clarinet - http://www.youtube.com/watch?v=9CkK-LM6Oe0 (warm, mid-high range)
The song played is Fight of the Bumblebee, coolest yet hardest song ever.
And flute is the best by the way (bias? maybe...)

If there's anything else you think we might have, please comment

from ihearthorses

GEOLOGY REVISION

GEOLOGY REVISION

Igneous: Meaning “from fire”, they are created when lava or magma cools at different rates. They contain crystal such as clear quartz, black mica and white/pink feldspar. Can be plutonic/intrusive where magma cools slowly underground, or volcanic/extrusive where they cool quickly above, often after an eruption.
-Used for decorative walls, floors, or desktops
-Eg. Pumice, Granite, Basalt, Obsidian, Gabbro

Sedimentary: Literally resembling, containing, or forming by a collection of sediments.
-3 main characteristics: No crystals, layers, grains
-Identified by layering, size and type of sediments.
-They all form underwater.
Sediments= Deposited piece of weathered rock or plant/animal remains
-Layers caused when grains/pebbles of different sizes settle at different times.
-Used for statues, paving, buildings and statues, but not as common due to acid rain wear. Polished limestone is too slippery for paving.
-Type of rock formed depends of place of formation and type of material
-Coal creates in forest floor where bottom layers are dried and temperature rises leaving coal
-Conglomerate formed in fast flowing river
-Mudstone formed in a still lake
-Limestone and coal aka biological rocks
-Eg. Breccia, Sandstone, Limestone, Shale, Mudstone, Siltstone, Gypsum, Coal, Conglomerate

Metamorphic: Meta meaning change and morphe meaning form.
Parent Rock Metamorphic Rock Main Cause of Metamorphism
Shale Slate Pressure
Limestone Marble Heat
Granite Gneiss Pressure
Sandstone Quartzite Heat
Conglomerate Metaconglomerate Heat
-Can be made of any other rock type
-Buried deep underground, change caused by heat from volcano and pressure from crust
-Used for statues, tables, roofs, slates, tiles, roads
-May be platy or flaky, distinct colour banding where minerals are squeezed into layers, distinct folding due to pressure
-Eg. Quartzite, marble, slate, schist, gneiss, Phyllite, Metaconglomerate

Weathering, Erosion:
-Sea action, wind, blasting of sand and soil, acid rain, and chemical reactions between water and ground
-Expansion of freezing water causes widening cracks which eventually break the rock
-Weathering: Where rocks are broken down into smaller pieces
-Erosion: Transportation of weathered rock
-Deposition: The weathered rock is laid down or deposited. Eg. From slowing wind or water

Rock Cycle Summary: Magma, crystallization, igneous, to weathering, erosion, deposition, to sediment, compaction and cementation, sedimentary, heat and pressure, metamorphic, melting, magma.

Layers of the earth: Crust, mantle, outer core, inner core.

Minerals: (rocks are made of minerals)
-Identified by characteristics including colour, lustre, transparency crystal system, crystal habits, cleavage, fracture, hardness, specific gravity, streak, other characteristics, associated minerals, notable occurrences, best field indicators.
-Rocks are composed of different minerals
-Most minerals contain crystals

Crystals: refer to previous revision

CuSO4 Crystals, Yum

Crystal Revision

These are COPPER SULPHATE CRYSTALS (CuSO4)

Method:

Part 1:

1. Weigh 7g of copper sulphate powder into a 250ml beaker using an electric balance
2. Collect 100ml of copper sulphate into a second beaker
3. Add 7g of copper sulphate to the solution and stir (to make solution saturated)
4. Heat beaker and stir to dissolve the solid powder (solution now supersaturated)
5. Pour the warm solution into the clean petri dish until 2/3 full and leave overnight (time is required in order for the solution to cool and solidify into crystals. The solution is now less but still supersaturated)
6. Cover the rest of a solution with a cardboard lid

Part 2:

7. Choose 2 seed crystals and place them on clean paper. (Shape/figure is more important than size as it is the template for the final crystal) Measure and draw one crystal. DO NOT TOUCH THE CRYSTAL (copper sulphate is poisonous and thus potentially harmful)
8. Tie a slip knot around the other seed crystal with cotton thread
9. Suspend the thread through the cardboard lid
10. Tip the remaining crystals back into the solution. You may need to scrape the crystals with a spatula (Crystals may have solidified onto the bottom of the dish)
11. Heat the solution until ALL of the solid has dissolved (This is increasing the saturation of the solution again)
12. COOL the solution in a shallow, cold water bath (otherwise the suspended seed crystal will melt)
13. Hang the crystal in the cool solution and leave to grow

Explanation:

As the supersaturated solution cools, the excess copper sulphate will solidify onto the seed crystal. Shape is maintained though the size will increase. Particles basically join evenly to the template as opposed to falling to the bottom of the beaker.
-Crystals grow by adding single layers of molecules at a time
-As the water cools and evaporates, the solid is forced out make these layers
-Crystal shape depends on the arrangement of atoms

Definitions:

Solution: Mixture of substance dissolved into another, solvent + solute = solution

Solvent: Does the dissolving (usually liquid, H2O)

Solute: Is dissolved (CuSO4 powder)

Unsaturated solution: Where the solution can hold more than what is dissolved into it

Saturated solution: Where the solution is holding exactly what it can. Adding excess will result in solid falling to the bottom, but solution itself remains saturated.

Supersaturated solution: Where excess solute is dissolved into the solution. It requires heat. When cooled, particles will be forced out of liquid and re-solidify.

Geog Revision

Plate Tectonics Revision

Wegener’s continental drift theory stages:
200 million years ago - Supercontinent Pangaea, Australia touching Antarctica and Indian Asia
180 million years ago - Split into Laurasia up north and Gondwanaland south
135 million years ago - Continents began to break up, Australia attached to Antarctica
65 million years ago - Further breaking up, Australia moved north-east into isolation
Today - Current positions
50 million years later – Australia to move further north
Types of plates:

Continental Plates:
 Carry land masses, continents, above
 Some also hold oceans, but they are named after the land. Eg. North American Plate
 Made of lighter, less dense rock. Eg. Quartz and feldspar
 Normally do not subduct
Oceanic Plates:
 Carry oceans above
 May carry small land masses, islands, but named after the ocean. Eg. Pacific Plate
 Made of heavier, denser rock. Eg. Mainly basalt, (granite?)
 Tend to subduct in a collision

Important information:
-Rocks deep underground can be studied through rocks from volcanoes and by looking at seismographs or seismic waves (shifting rocks create energy)
-Deep underground, the high pressure keeps rocks solid by compacting and compacting particles (liquid takes up more space than solid)
-Middle of earth probably made of iron, as rock alone would not be able to make up the weight (measured using Cavendish balance) and magnetism of the earth which make compasses work is based on this iron core. The field of magnetism from N to S poles protect the earth from solar winds
-The middle of the earth is liquid outside and solid inner section
-Like gases, hot molten rock will rise (to form volcanoes) and cool rock will sink
-Volcanoes are created when molten rock rises through up through the crust
-When a plume of hot rock pushes through the mantle, cooler rock is forced aside causing volcanic ridges. The old crust moves aside and magma fills the gap to develop new crust
-Positions on the edge of a plate are more tectonically active. Australia is in centre so it is not
-A normal fault is where rocks are pulled apart and one side drops down
-Large faults can cause earthquakes
-Folding and breaking of rocks plus grinding of one plate under another can cause earthquakes to occur
-When rocks break and slip, earthquakes can occur
-Trench is a long narrow valley on the ocean floor
-Subduction is the action of a plate (usually oceanic) sliding beneath another plate upon collision
-When an oceanic plate subducts and causes an earthquake, a tsunami can also occur
-Subduction zone is the area where a plate subducts
-Plates are constantly on the move, they move at a rate of 5 to 15cm per year

Convection Currents:
This is the heat-driven motion that causes plates to move and rocks to travel in a circular motion within the earth. They are within the mantle
Currents moving away from each other = diverging = crust pulled apart
Currents moving toward each other = converging = crush pushed together

Plate Boundaries:

1. Divergent/Constructive Boundary
-Movement of plates away from each other
-Plates can be oceanic or continental
-Gap caused called a rift or ridge
-Magma fills rift, volcano formed
-New crust created
-e.g. Mt Kilimanjaro, East African Rift, Mid-Atlantic Rift, Iceland

2. Convergent/Collision/Destructive Boundary

-Plates move toward each other
-Ocean to continent = oceanic crust subducts and melts, land on continental crust folds upward, volcano and rift forms. E.g. Mt St Helens, USA

-Ocean to ocean = one piece of crust subducts and melts, volcano (underwater) and trench forms. E.g. Japan, Indonesia, Caribbean Islands, Philippines (island arcs)

-Continent to continent = none or very little subduction occurs; continents on top of the plates collide and fold upwards to form mountains. E.g. Himalayas (Indian and Eurasian Plates), Andes (fold mountains?)

3. Transform/Conservative Boundary
-Plates slide alongside each other
-Can be oceanic or continental
-May move in the same or opposite direction
-Causes a fault e.g. Sand Andrea Fault, California (Pacific and North American Plates)

Helpful sites:
http://geology.com/nsta/convergent-plate-boundaries.shtml
http://www.waterencyclopedia.com/Oc-Po/Plate-Tectonics.html