ELECTRICITY

-All matter is made of atoms
-In the nucleus are positively charge protons and neutral neutrons
-Surrounding are negatively charged electrons
-Usually, no. electrons = no. protons
-More protons than electrons = positively charged
-More electrons than protons = negatively charged
-Equal pos and neg charge = neutral or uncharged

Static Electricity:

-charge = addition or removal of ELECTRONS (unlike protons, they are not held together and so can be easily moved)
Static electricity is due to the buildup of charge in some objects by:
1. Friction: neutral to neutral: Rub plastic with wool--> electrons move from wool to plastic --> wool is positively charged having lost electrons, plastic is negatively charged having gained electrons
2. Contact: charged to neutral: neutral substance gains or loses electrons
-Static electricity can leak slowly through substances such as rubber or air

3 LAWS:
-Unlike charges ATTRACT
-Like charges REPEL
-Charged objects ATTRACT uncharged objects*
Note: The larger the charge difference, the stronger the attraction/repulsion
*eg. Neg rod near neutral paper, pos from paper is attracted to surface closest to the rod, if strong enough, paper may be pulled to rod due to attraction
Other examples:
-wiping surfaces with a cloth leaves electric charge which attracts light, neutral dust particles
-TV and computer screens also attract dust when in use
-Walk on a carpet, friction gives electric charge
-Small electric shock when charges move very quickly to/from your body
-Moving car shares electric charge with passengers, shock as charge moves to the ground via body
-Lightning occurs when movement of particles within a cloud causes the top to be positively charged and bottom to be negatively charged, when the neg builds up it moves to ground or other clouds as a spark of lightning

-An electric field is the area around a charged object

THE ELECTROSCOPE:
-Positive charges DO NOT move
Situation 1: Neg rod, neg repelled down, leaf diverges because negatives are now all at the bottom and like charges repel
Situation 2: Pos rod, neg attracted to the top, leaf diverges because only pos is left at the bottom and like charges repel
Situation 3: Pos rod, neg attracted to top, pos rod touches, neg jumps onto the rod, rod taken away, leaf diverges because only pos is left on the electroscope and like charges repel
Situation 4: After situation 3, finger touches electroscope, pos attracts neg from your finger, electrons jump to electroscope, leaf goes back to original state (this is earthing)

Circuits and Currents:

-For a globe to light up, the circuit must be complete
-A closed switch will complete the circuit
-An open switch will make the circuit incomplete
-A complete electrical circuit is a continuous pathway where electricity can flow
-Power supply: provides electrical energy, battery or power point
-Load: electrical energy is changed into other forms of energy, globe
-Conducting path: allows electrical energy to flow around the circuit, wires
-Current: measure of how much electrical charge passes through a point in the circuit in one second or rate of flow of charge, amperes or amps or A
-Voltage (aka potential difference): energy carried by the charge or amount of energy contained in electrons flowing in an electric circuit, unit is volt



SERIES OR PARALLEL:
-Series: all components are connected in a single path so there is only one path for electrons to flow
-the more light bulbs, the dimmer all the lights will be (with 3 in a series, each gets one third of total voltage)
-if one goes out, they will all go out
-it doesn’t matter which globe goes out
-Parallel: there is more than one continuous path for the electrons to flow
-with more light bulbs, the brightness is still the same as having just one (each globe uses the full voltage of the battery)
-if one goes out, others are unaffected
-it (obviously) does not matter which one goes out

USING A MULTIMETER:
To measure current (in amperes, A) we use the multimeter as an ammeter connected in series
To measure voltage (in volts, V) we use the multimeter as a voltmeter connected in parallel
-Below, the ammeter would replace one globe in series circuit 2, the voltmeter would replace one globe in the parallel circuit



CONDUCTORS AND INSULATORS
The size of the electric current depends on resistance.
-little resistance = large current
-materials with little resistance = conductors = most metals
-materials with a lot of resistance = insulators = many nonmetals such as air, rubber
-filaments, in heating elements, have some resistance causing charge to release energy in the form of heat as it tries to get through
Note: Current is measured in A (amperes) or mA (milliamperes). 1000mA=1A

BATTERIES
-a battery is made of two or more cells, although it more often refers to a single cells (eg the things we put in torches)
-A cell has two electrodes and a substance for electric charge to flow through (electrolyte)
-when two electrodes are joined by a conducting path, a chemical reaction releases charge and allows current to flow
-dry cells are filled with a paste of chemicals
General purpose dry cell:
-electrodes are a central carbon rod on pos terminal and zinc case touching the neg terminal
-reaction between zinc and paste = charge allowing current to flow
-separating layer stop reaction while battery is not in use

-Alkaline cells allow greater electric current to flow
-ideal for heavy-duty torches, digital cameras

-Mercury cells have a steadier voltage than dry cells
-ideal for hearing aids, watches, calculators

LEMON/GRAPEFRUIT BATTERY
-Lemon/grapefruit with 2 metals, wires and an LED
-We know it works because the LED lights up
-The more fruit connected in series, the higher the electric current
-The electrode = the two metals
-Electrolyte = acid in the lemon/grapefruit juice

-Lead dioxide car batteries and nickel-cadmium mobile phone batteries are rechargeable
-A battery charger can be used to reverse the reaction that causes electric current to flow

:D

Nevermind, i found the fish. But still please feed.

:'(

I think a fish died. There were 7. Please feed

Geography Quiz

Climate Change Revision:

Greenhouse effect is entirely natural:
-Greenhouse gases, esp. water vapour, form part of Earth’s atmosphere
-Gases allow sun’s energy to enter atmosphere
-Energy radiated back, some trapped, some radiates into space

Enhanced greenhouse effect, result of human activities:
1. Solar heat, incoming solar radiation passes through atmosphere, warming land and sea
2. Heat trap, with more co2, more heat is trapped
-CFC’s, cause thinning of ozone layer
-Deforestation, produces co2
-Fossil fuels, releases large amounts of carbon
-Nitrous Oxide, from nitrogen-based fertilizers and fuel
-Vehicles, exhaust is source of heat-trapping gases
-Methane, from people and animals
-Oceans, unable to absorb as much co2 as is produced, increased temperature reduces this ability

Enhanced greenhouse effect
-->increased average global temperature and sea surface temperature
-->sea levels rise, changed ocean circulation, changed atmospheric circulation
-->Leads to climate change
-->Affects coastal areas, weather, agriculture, human health, ecosystems/habitat

Factors causing climate change:
-The increase of fossil fuels; coal, oil and natural gases contain carbon which is released when burnt. 20billion tonnes of co2 produced annually, 10billion reach the atmosphere, the rest absorbed by plants and oceans
-Deforestation; Clearing, burning and decay of vegetation release co2 that is stored in trees into the atmosphere. Also, reduction in vegetation means there are fewer plants to absorb/store co2
-Increase in methane production; Agricultural production where herbivorous animals such as cattle and sheep release methane, as well as rice paddies and other forms of irrigated agriculture. Land fill, forest fires and extraction of coal or gas also contribute.
-Increase in nitrous oxides; fossil fuel burning, motor vehicles and nitrogen-based fertilizers in agriculture are all responsible.
-Chlorofluorocarbons; once used in devices such as fridges, aircon, plastic foam and aerosol cans, they have been phased out since 1989 but once released, last for up to 100 years in the atmosphere.
-Increase in water vapour; indirectly, atmosphere warms through increase of other gases, and so temperature rises, evaporation increased and thus water vapour levels increase

INCREASE IN HUMAN POPULATION, NEED TO FEED PEOPLE, INCREASING MODERNISATION OF SOCIETY

Global warming: increased will be distributed unevenly across the world, differences between land and sea temperatures, changes in physical process affecting climate
Thermohaline circulation: Aka the great conveyer belt, it is the movement of ocean water powered by differences in salinity and temperatures. Air in the atmosphere is constantly moving as different parts of the globe receive different amounts of heat from the sun.

Global warming alters ocean circulation and heating, thus air above also moves differently resulting in shifts of the existing climatic belt
Sea level rise:
1. When water warms it expands, causing sea level rise
2. Warmer temperatures melt polar ice caps and mountain glaciers, adding to sea level

Impacts on weather:
Weather is driven by heat from the sun, causing circulation in the atmosphere and hydrologic cycle. Additional heat speeds up the system, increasing movement of air and water
1. Rainfall; Atmosphere is able to hold more water vapour, thus some places will be drier and others will be wetter. In general, dry places will become drier, wet places wetter. Flooding, landslides, and drought will increase.
2. Storms; tropical cyclones need warm water to form, thus temperature increase will increase distribution and intensity of these storms.
3. Heat waves; more extreme temperatures occurring due to climate change, affecting people crops, livestock, fish and wildlife. Wildfire risks also increase.

Impacts on coastal areas:
-islands submerged, increased flooding damage to crops and buildings meaning food production is decreased and money spent on protection, fresh water contaminated by saltwater

Impact on ecosystems and habitats:
-species forced to migrate, others that cannot adapt will become extinct, some habitats such as coral reefs destroyed by warmer conditions, water temperatures rise killing organisms and affecting food chains and ecosystems, migrating/distant species incur flow-on impacts

Impacts on agriculture:
-some plants unable to grow in increased temperatures, weeds, insects and plant diseases will expand, soil moisture changes may increase/decrease which kill plants that are unable to adapt, and increased co2 should increase photosynthesis and stimulate plant growth

Impacts on human health:
-freshwater shortage due to contamination, increasing drought, water quality affected so diseases such as cholera spread, range of diseases carried by vectors increase, more extreme natural disasters cause death more air contaminants from expanding deserts affect those with respiratory conditions.

Combating global warming:
-global policies such as Montreal protocol of 1987 and Kyoto Protocol of 1997 reducing emissions
-carbon taxes, energy-efficient technology, incentives for business to reduce, education, public awareness, renewable energy, reforestation, incentives to individuals, setting targets
-have energy-efficient homes, plant trees, reduce consumption (plastics, cans), use public transport locally grown food, bikes and walking car that suits needs, encourage government

EATING TO LIVE

EATING TO LIVE

Atoms (may not be in test, but it’s in my notes):
All substances are made of particles called atoms
Elements: composed of one type of atom
Compound: when 2 or more different elements are chemically bonded
Molecule: separate units of 2 or more molecules (eg. Water molecules)
Mixture: 2 or more elements are found together but not chemically bonded

We eat for:

-energy
-health
-nutrients: vitamins, minerals, fats, fibre/roughage, protein, carbs, water
-life
-growth and recovery
-to function properly
-warmth
-fun
All living organisms require energy; in animals cellular respiration supplies this
Oxygen + glucose = carbon dioxide + water + energy

Digestion:



a: salivary glands – Makes saliva containing enzymes which break down starch
b: liver – makes bile which breaks down fats, controls blood sugar, destroys poisons and stores vitamin A, D and iron
c: gall bladder – bile is stored here, which breaks down fats into small droplets so that lipases can access them
d: bile duct – tube that carries bile from gall bladder to duodenum
e: duodenum – site of digestion for carbs, fats and proteins, short part of small intestine connecting to stomach
f: appendix: kind of useless, may help fight some diseases
g: anus: faeces passes through
h: rectum: final part of large intestine, faeces storage
i: large intestine: absorbs water, vitamins and minerals from undigested material which passes through
j: small intestine: digestion of fats carbs and proteins; foods and liquids are broken down into nutrients which are absorbed into bloodstream
k: pancreas – makes alkaline pancreatic juice to neutralise stomach acids and enzymes
l: stomach – hydrochloric acid and muscle movement mixes food with gastric juice to break down protein.
m: diaphragm*
n: oesophagus – carries food from mouth to stomach using peristalsis (involuntary muscle contractions)
o: trachea*
p: mouth - food and saliva mixed, teeth for mechanical digestion
q: nasal passage*
r: pyloric sphincter – band of muscle that regulates movement of food out of the stomach
caecum: in plant-eating mammals it breaks down cellulose which is found in plant cell walls
ileum: last section of small intestine, absorbs nutrients
*m, o, and q are probably not needed

Process of digestion:

-food enters the mouth where it is chewed with teeth and mixed with saliva to break down starch
-travels down the oesophagus to the stomach
-stomach churns food, hydrochloric acid kills germs and allows enzymes to work
-food travels to the first part of the small intestine, the duodenum. Food mixes with bile from the gall bladder and pancreatic juices with enzymes from the pancreas. Carbs fats and proteins are digested. Minerals are absorbed
-food goes through small intestine; nutrients absorbed into bloodstream
-indigestible food continues to large intestine; water, vitamins and minerals are absorbed. Faeces is formed
-Faeces stored in rectum
-Passes through anus

Mechanical and Chemical digestion:

Mechanical: physically breaks down food into smaller pieces. (chewing with your teeth, stomach churning)
-3 types of teeth; incisors for biting and cutting, canines for tearing and grasping, molars/premolars for grinding and crushing
Chemical: where chemicals in your body react with the food which change the substances in food into simpler chemicals that can be absorbed into you blood (amylase in saliva, protease, lipase)


Enzymes:

-Assist chemical digestion by increasing rate of reactions
-The smaller an object is, the higher its volume to surface area ration becomes
-In digestion, this means smaller food particles are more exposed to digestive chemicals and enzymes
-Made of protein
-If enzymes become overheated they become denatured so they can’t work
-Substance being broken down is the substrate
-Resulting substance is the product
-Are specific for jobs they do
-Amylases: break down carbs (eg starch) into glucose
Produced by pancreas and small intestine
-Lipases: break down fats/oils into fatty acids and glycerol
Salivary glands, pancreas, small intestine
-Proteases (such as pepsin): break down protein into amino acids
Stomach, pancreas and small intestine
-Hydrochloric acid: kill bacteria and help produce acidic conditions for enzymes to work
Produced in stomach

Carbohydrates:

-rice, pasta, bread, cereal, oats, potato
-energy source
-extra energy stored as starch in plants, glycogen in animals
-cellulose in plant walls=fibre/roughage to maintain cholesterol and glucose levels and keeps food moving along the digestive system
-building blocks are glucose
-in fruit = fructose
-in milk = lactose
-normal sugar = sucrose
-starch, occurs in plant cells as grains. Each grain is surrounded by a membrane which comes apart when cooked

Proteins:

-meat, poultry, fish, eggs, dairy, nuts, lentils, beans soy, wheat
-molecules are enzymes, antibodies (defending the body), structural such as keratin and hormones
-major function – growth and repair
-made of chains of amino acids
-some amino acids must be eaten, others produced by the body

Fats:

-butter, lard, dripping, oil, margarine, nuts, fried food
-Animal fats become liquid when heated, plant fats usually liquid at room temperature
-energy
-in mammals, stored under skin for warmth and organ protection
-building blocks are fatty acids and glycerol
-saturated fats: maximum amount of hydrogen possible, they increase cholesterol and risk of heart disease. Animal fats are saturated.
-polyunsaturated fats: contain considerably less hydrogen than maximum amount. Plant oils contain high proportion of polyunsaturated fats which reduce cholesterol.


Nutrient tests:

Reagent Nutrient
Sugar Diastix
Starch Iodine
Protein Sodium hydroxide + copper sulphate
Fat Brown paper
Water None, this was used as a control for comparison

Some definitions:

Ulcer: a break in the mucus lining of the stomach
Quantitative: Deals with numbers and measurable information such as lengths, weights, ages time
Qualitative: Deals with descriptions and can be observed but not measured, such as colours, tastes or opinions
Emulsify: separate (mechanical digestion); bile emulsifies lipids like fats so that it has a larger surface area
Denatured: cannot go back to original state so cannot function
Carnivores: eat meat
Herbivores: eat plant material (will have a larger caecum)
Omnivores: eat plants and meat (may have larger caecum)
Insectivores: feed on insects
Insulin: turns excess glucose to glycogen for storage

I will update tomorrow night, tell me if i missed anything, you've probably been in more lessons than I have :)

Hello,

Just a hint; the fish will not die if you overfeed them (glares at certain people, hint hint)

ihearthorses

Hi Everyone,

What a fantastic test week people seem to have this week! :)

More importantly, THESE REVISION SHEETS ARE NO LONGER FREE.

You MUST feed the fish on the right to use them, or they will eat you (the fish, not the revision sheets)

Nah, jks, but please do feed them

From
ihearthorses

Geography Revision Test 1

Glossary:

Agriculture: The farming of animals or crops

Arable Land: Land that can be used for growing crops

Deposition: The laying down of sediment that has been transported by wind, water or ice

Drainage Basin: An area of land where all surface water converges on a single point

Drought: A shortage of rain which adversely affects plant and animal life

Dryland Salinity: Loss of farm and grazing land due to rising salt levels

Erosion: The wearing away of the land or soil by wind or water

Fertile Soil: Rich in nutrients for growing crops

Groundwater: Water located in rock pores beneath the Earth’s surface

Horticulture: The farming of plants or flowers

Infiltration: The seepage of water into the soil

Irrigation: The adding of water to the land in order to water crops (sprinklers, diversion channels, pipes, ditches)

Land Degradation: Decline in quality of soil, water or vegetation conditions

Land Use: The intended purpose of an area

Marginal Land: An area with low, unreliable rainfall, poor soil or steep slopes which make the growing of crops risky

Resource: Anything that occurs naturally or is man-made which fulfils a need or want of people

Rural: Country regions where activities such as agriculture, horticulture, forestry, and mining dominate

Salinity: Level of saltiness

Sustainability: meeting the needs of the present while ensuring that we can meet the needs of the future

Topsoil: The uppermost level of soil which determines yields in agriculture

Transpiration: Water loss from plants through the stomata of their leaves, into the atmosphere

Urban: Large, permanent settlements such as cities or towns with little agricultural employment

Watertable: Upper level of the aquifer or groundwater layer

Wetland Salinity: Saltiness that results when overuse of water and irrigation causes rising watertables

Drainage Basins:

What is a drainage basin?
A drainage basin, or catchment, is an area of land that serves as a funnel to direct rainfall and excess water to a single point, where the waters flow into another water body such as a river. Adjacent drainage basins are separated by hills, mounds, ridges, or mountains. The term drainage basin refers to the whole area from watershed to watershed.



Diagram:



Catchment Area: Area from which rainfall flows into a river, lake or reservoir
Confluence: The point at which 2 rivers join
Floodplain: Low-lying land adjacent to a river, formed mainly by river sediments. It is subject to flooding.
Headwaters: The region where rain or melting snow originate to feed the rivers (often mountains)
Mouth: he point at which the river flows into a sea, ocean or lake
Source: The region where rain or melting snow originate to feed the rivers (often mountains)
Tributary: Any stream that flows into another stream
Watershed: The high point which separates adjacent drainage basins topographically




The Murray Darling Basin:

In the map above, the Murray Darling Basin is the brown area in South-east Australia. It is approximately one million square kilometres, and around 1/7 of the continent. It contains Australia’s two longest rivers; the Murray and the Darling, hence the name. It is bordered by the South Australian Coast, Lake Eyre, Bulloo-Bancannia, North-east Coast and South-East Coast drainage divisions.

Reasons for Land Degradation:

Processes are: Wind, water and salinity

1. Deforestation
The removal of trees for firewood, commercial logging or land clearing for farming or settlements

2. Overgrazing
Soil is exposed due to vegetation consumption by animals, meaning plants cannot regenerate

3. Compaction
Infiltration reduced by heavy machinery or hard-footed animals, making it difficult to use the land

4. Poor Land Management
Use of inappropriate farming methods for the type of land and/or soil

5. Acidification
Overuse of chemical fertilisers rather than natural fertilisers such as organic matter

6. Fires
Bush ad Scrub fires strip the soil of plant material

7. Pollution
Dumping of scrap metal, plastics, packaging and building rubble

8. Mining
Damages soil and underlying structure of the land

Remember this using CAMP FOLD (L as in land from poor land management)

Water Erosion

-Once the original plant cover has been removed, soil can be carried away by heavy rain and deposited elsewhere
-On sloping land, the excess water on the soil surface runs down the slope and carries away a thin layer of soil (SHEET EROSION)
-Water may flow in a series of small channels or grooves in the land. These are RILLS
-When rills become so large that they cannot be crossed by farm machinery, they are known as gullies. When left unattended, gullies can become many metres deep and many hundreds of metres long
-Results in instability of soil


Wind Erosion

-Wind can move soil thousands of kilometres
-Great deal of topsoil can be blown away
-Crops lost because they are blown out or covered in soil
-Soil structure can be affected (rills and gullies may form)
-Infrastructure damages with soil deposited over houses/ fences in heavy dust storms

Less than 1mm sediments = CREEP
0.1-1mm sediments = SALTATION (jumping)
0.001-0.1mm sediments = SUSPENSION

Salinity

Dryland salinity: Rising Salt (in non-irrigation areas)
Wetland salinity: Rising watertables (due to irrigation)

-Trees and deep-rooted plants removed due to European Settlement and later human needs, meaning there is nothing to control groundwater levels
-Irrigation causes rising groundwater
-Rising groundwater causes rising watertable
-Rising watertable brings dissolved salt closer to the surface, causing saline soil when within 2metres
-Crops unable to grow
-Infrastructure may be damaged
-Saltier groundwater and surface water


Geography Revision T1

Solutions:
1. Reforestation; the growing of more plants in order to improve and stabilise soil, meaning it will not be so easily washed away
2. Strip planting; Altering rows of regular crops with cover crops so that when there is heavy rain, cover crops will hold the soil in place
3. Avoid farming on steep slopes; this reduces the risk of water erosion, as the water will not flow downhill and thus the soil will not be carried away
4. Salinity-limit placed on amount of water that can be taken from the Murray
5. Saline water pumped away and watertables kept low
6. Water should be used more efficiently
7. Crop rotation, so that soil has time to regenerate
8. Reduce overgrazing, irrigation and deforestation
9. Limit destructive human activities
10. Switch to salt-tolerant crops

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