IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => IGCSE/ GCSE => Reference Material => Topic started by: Galleria on October 02, 2010, 11:51:12 am
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Hi,
My IGCSE exams are in less than a month and I'm giving Coordinated Science and I'm really not all that prepared. I have a few problems in Math as well but I have no problem in any of the others. I need to finish understanding everything by the 20th of October of these two subjects so that I can get A*'s in both. Our school's mock Math exam was ridiculous easy as out of 60, 35 got A* and that's the grade they're sending for the expected grade. By the way, can anyone tell me if IGCSE sends the percentage of scores too?
And, yes, anyway, I have a lot of problems in Math and Science that I need to clear out by the 20th. By Friday, I must finish with Physics (the part of Coordinated Science). These are my problems for Coordinated Science;
- Ionisation process of Hard Water
- Rocks... oil store in them.. and that millions of years fossil fuel thing
- Hooke's law (I did a test after studying myself and got 18/25 . I suck at it . lol)
- The lens stuff from Light
- Magnetism XX
- Radioactivity (well I haven't really studied so nvm this) XX
- Bone & Muscle
- Heart
- Ecology XX
- CRO (Cathode Ray Oscilloscope)
- Prisms & Parallel-sided block thing . I need to understand this for MCQ
- Ethene -> What is hydration, hydrogenation?
- Static Electricity ( I NEED SOME REAL HELP WITH THIS . FRICTION AND STUFF THAT HAPPENS HERE)
- Plants XX
- Menstruation
- Glass, bonding (I don't understand Giant Molecular and the Metallic Bonding stuff)
- Haber Process, Contact Process, Ostwald Process XX
- REED SWITCHES ???????
- Nuclear Fusion/Fission ?
- Constructing Keys for Bio Ecology
- Iron Extraction process XX
I have more but they are to be studied, not helped with.
lol , could someone explain a few of them to me ?
I really suck at the things I listed. Well not know anything, but I don't understand them well.
And for Maths :
- Vectors
- Transformation (I don't get a single thing. It takes me half an hour to do one question)
- Is there like a formula for symmetry ?
- How do I take out the Increase/Decrease Percentage?
- Probability
- Graphs
- Parabola
- Loci.
:D .
So that's about it .
could someone like help me with it bit by bit ? I really will be in trouble otherwiseee!
The ones that have "XX" don't need special attention . I just could use some resources for them though .
:D
PLEAAAAAAAAASE HELP ME!!!
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Read this (http://www.darvill.clara.net/enforcemot/springs.htm) first.
Hookes Law in short states that the EXTENSION of a spring is directly proportional to the load (in Newtons) extending it.
What lens stuff exactly ? Check THIS (http://astarmathsandphysics.com/igcse_physics_notes/igcse_physics_notes_drawing_ray_diagrams_for_thin_lenses.html) out.
For CRO. http://www.doctronics.co.uk/scope.htm READ BELOW TOOO !!!!
cathode ray oscillascope. has 6 parts.
the filament: it goes through thermionic emiision(where a substance is heated it releases electrons) this filament is heated and releases electorns with negative charge.
the anode grid: it has a positve charge. this controls the nrightness (ill tell u how later)
the cathode grid: it has a negative charge, this allows the beam of electron (the electrons emitted when tht filament was heated)
the y plates:hese have plates with (+) and (-) charge and are attached vertically to each other on the tube of the CRO. this helps the beam of electrons move up and down so the beam of electrons spread evenly (up and down) on the screen.
the x plate: these have plates with (+) and (-) charge and are attached horizontilly to each other on the tube of the CRO. these help the electrons move (left and right) as it hits the screen.
the screen: at the end of the CRO is the screen (made of fluroscent usually) when electorns hit this screen it glows.
without x plate and y plates u will see the beam of electrons hitting one point of the screen only (so only tht part glows) for eg:on TV (just an example) , if with out x plates and y plates, picture can only be seen as a spot of light (picture) on the screen. but with x and y plates the electrons are able to reach both (up and down) and (right and left) with the help of y plates and x plates respectively. (ill tell u how they work later))
how does the OCR work?
first the filament is heated, beams of electrons are emitted (this is callerd thermionic emission). they go throu the cathode. what does cathod do? Cathode are negatively charge (-) and so are the beam of electrons, so repulsion take place due to similar charges allowing some beams of electrons to "stay back". This control the brightness cuz "the more number of electrons hittin the screen, the brighter the pic comes on the screen". ok, then the beams pass through the anode. what does the anode do? Anode is positively charged (+) and the beam of electrons are oppesitely charged. this anode atracts the beam of electron giving the "boost" or "acceleration" and to travel in a straight line (beam). then it reaches the Y plates. as i told u the help the electrons move up and down . they are plates with voltages (charged with (+) and (-))). they are GIVEN WITH A.C VLTAGE because if it was D.C then the elctrons would only move up OR down depending on the position of the positively charged plate ( as beam of electron is negatively charged). u see, A.C current changes its direction so the plates change their charges, whic means (+) become (-) then later (-) becomes (+). so (+) charge changes its positon and so does the beam of electron which changes its direction of deflection. this helps the electrons to touch both up and down of the screen.
the X plate are same, except they help the electrons to move right and left they are also charged except tht they are aranged horizontally. they are time base. the work with time, how? by letting the voltage between these plates go 0 then after sometime go to a certain value. how tghis helps? as the voltage has acertain value thts not 0 the beam deflects to towards positively charged plate. then when after a certain time it the voltage goes 0 immediately. this all ows the beam of electrons to GO BACK its old path (which was before deflection at X PLATE), then vise versa. this helps the electrons go left and right on the screen.
U might ask what in x plate there is time base and in y plates are AC current? why cant the put AC on the xplates too? This is because i think tht the time base system helps beam to go in the REQUIRED or aprropriate horizontal path.
then finally the electrons reaches the screen in every direction (with the help of x and y plates) which causes the whole fluroscent screen to glow or lit.
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For Metallic Bonding memorise this definition for full marks:
It involves a lattice of positive ions surrounded by a sea of negative electrons. The electrons are mobile. There are strong electrostatic forces between the ions and electrons.
Macromolecules are giant covalent structures e.g. Diamond.
Hydration
Is where an Alkene is reacted with STEAM to turn it into an alcohol.
You need Phosphoric acid catalyst, 300 centigrade and 60 ATM for this reaction.
Hydrogenation
Is basically adding hydrogen to an alkene, forms an alkane. You need a nickel catalyst and 150degrees for this reaction.
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For ALL the IGCSE Chemistry reactions and the conditions required see this : https://studentforums.biz/references-and-resources/chemistry-guide-a-guide-to-special-conditions-needed-for-various-reactions/ (https://studentforums.biz/references-and-resources/chemistry-guide-a-guide-to-special-conditions-needed-for-various-reactions/)
I dont do Biology, but this is an awesome site for any bio topics http://www.biology-questions-and-answers.com/index.html (http://www.biology-questions-and-answers.com/index.html)
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For the prisms and parallel sided blocks thingy :
(http://www.school-for-champions.com/science/images/light_dispersion1.gif)
For the prism notice how the light bends when hits the prism the first time and then DIFFRACTS. Once the coloured spectrum reaches the second prism surface it BENDS DOWNWARDS again.
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For percentage decrease or increase
Use the formula : original amount - new amount
original amount * 100
What graphs do you have an issue with ?
What do you not understand in probability ?
For Loci read the two scanned pages below
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Static Electricity : http://www.s-cool.co.uk/gcse/physics/static-and-current-electricity/static-electricity.html
Reed Switch : is basically two wires passing through a glass bulb. Around the bulb is a wire.
When an electric current passes through the wire around the bulb a magnetic field is induced that magnetises the two wires in the bulb.
The wires in the bulb become opposite poles, attract each other and close to complete a circuit.
The wires in the bulb are normally separated and NOT touching. They only come into contact when magnetised.
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OH MY GOSSSSSSSSSSSSSSSSSSSSSH!
THANK YOU SO MUCH !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
:O :O :O :O !!!!!!!!!!!!
GO ARIIIIIIIIIIIIIIIIIIIIIIIIII!
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OH MY GOSSSSSSSSSSSSSSSSSSSSSH!
THANK YOU SO MUCH !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
:O :O :O :O !!!!!!!!!!!!
GO ARIIIIIIIIIIIIIIIIIIIIIIIIII!
No worries.
I've modified my previous posts - some pictures have been added and I added some scans regarding Locus.
So refresh this page from time to time and check each post to ensure you've not missed anything new. I'll be adding new stuff all the time.
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Graphs - I need to learn all the general stuff . lol
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Graphs - I need to learn all the general stuff . lol
You're not being very specific. Do you need stuff regarding histograms or CF graphs ?
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CF Graphs . lol
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CF Graphs . lol
And what is it you dont understand in CF graphs ? Please, be specific. I dont have the whole night to waste typing stuff for you.
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OMG . don't get angry . don't botheeeer . this is enough .
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By the way, can anyone tell me if IGCSE sends the percentage of scores too?
For your information, I m from India and, I got the % mark sheet!
Don't know about the other zones.
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I wasnt being angry ::)
I am just a good Samaritan thats here to help.
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Okay;
let me make it easier for you.
I don't understand these things in my syllabus:
- be able to distinguish between transverse and longitudinal waves and appreciate the circumstances in which either or both might occur ????
- appreciate the way a wave can be reflected off a plane barrier ?????????????????????
- appreciate the way in which a wave can change direction as its speed changes ? WTF ?
- appreciate how reflection and refraction properties can be applied to understand the transmission of light down an optical fibre
- appreciate how sound levels can be measured and appreciate the desirability of reducing noise levels yet recognise the problems involved in doing this
-understand that diffraction and the speed of light in glass, in relation to that in air, are some evidence for the wave nature of light
-appreciate how energy can be transferred from waves and how it is possible to be selective in making that transfer
-appreciate that earthquakes involve the passage of waves through the Earth
-understand that wave motion is a useful way of describing and explaining the behaviour of light and sound
-appreciate the nature of colour vision
in terms of primary and secondary
colours
-be able to identify wavelength with
colour in light
-know how sound can be transmitted
through air as a wave
-be able to relate the loudness and
pitch of a sound to the amplitude and
frequency of the sound wave
lol that's around it
:D
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Hmm..all of it? :x
Give me some time, will you? ;)
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looool alright! :D
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- be able to distinguish between transverse and longitudinal waves and appreciate the circumstances in which either or both might occur
Transverse waves
Vibrations at right angles to the direction the waves travels.
i.e. When a disturbance is created, the molecules 'vibrate', basically up and down, which is perpendicular to the motion of the wave.
Graphical representation
(http://www.dbooth.net/mhs/chem/wave-transverse02.gif)
[Right-click view image]
Longitudinal waves
Vibrations in the same direction as the waves travels.
i.e. When a disturbance is created, the molecules 'vibrate' to and fro, forwards and backwards which in in the direction of the wave motion.
(http://www.antonine-education.co.uk/physics_a2/module_4/topic_4/wav_9.gif)
During earthquakes, both occur simultaneously : http://en.wikipedia.org/wiki/Earthquake_waves
Though you don't have to know the details.
-appreciate the way a wave can be reflected off a plane barrier
Light waves, sound waves, examples of transverse and longitudinal respectively reflect when hit a surface.
Regular and irregular refelction of light
(http://www.physicsclassroom.com/class/light/u12l1a1.gif) (http://www.stevesportfolio.co.uk/work/easy_gcse/img/wave_img/reflection1.gif)
Uses of reflection of sound (echo)
(http://www.jfkscience.org/Physics/Notes/WAVES_files/image108.gif) (http://www.coml.org/edu/img/bottom-penetrating_sounders_01.gif)
-appreciate the way in which a wave can change direction as its speed changes
I think this is the explanation : relating it to the previous explanation, the phenomena can be called as refraction.
When a light wave passes form an optically denser median to a rarer medium or vise versa the speed as well as direction changes.
(http://lcogt.net/files/jbarton/glass%20block%20refraction.png)
In the picture : A ray of light enters from air into glass
- appreciate how reflection and refraction properties can be applied to understand the transmission of light down an optical fibre
Light can be trapped by total internal reflection inside a glass rod and 'piped' along a curve pat. A single, very thin glass fibre behaves in the same way.
See, you must know what is critical angle of a substance for the explanation. Critical angle is when the angle of refraction is 90*.
http://www.medrounds.org/optics-review/uploaded_images/Figure18-774908.jpg
In the picture : R2 shows the critical angle.
If this critical angle is exceeded, total internal reflection occurs. R3 in the picture shows total internal reflection.
Optic fibres use this principle to propagate light rays or any other electromagnetic radiation to long distances.
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:D THAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAANKS :D!!!!!!!!
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- be able to distinguish between transverse and longitudinal waves and appreciate the circumstances in which either or both might occur
Transverse waves
Vibrations at right angles to the direction the waves travels.
i.e. When a disturbance is created, the molecules 'vibrate', basically up and down, which is perpendicular to the motion of the wave.
Graphical representation
(http://www.dbooth.net/mhs/chem/wave-transverse02.gif)
[Right-click view image]
Longitudinal waves
Vibrations in the same direction as the waves travels.
i.e. When a disturbance is created, the molecules 'vibrate' to and fro, forwards and backwards which in in the direction of the wave motion.
(http://www.antonine-education.co.uk/physics_a2/module_4/topic_4/wav_9.gif)
During earthquakes, both occur simultaneously : http://en.wikipedia.org/wiki/Earthquake_waves
Though you don't have to know the details.
-appreciate the way a wave can be reflected off a plane barrier
Light waves, sound waves, examples of transverse and longitudinal respectively reflect when hit a surface.
Regular and irregular refelction of light
(http://www.physicsclassroom.com/class/light/u12l1a1.gif) (http://www.stevesportfolio.co.uk/work/easy_gcse/img/wave_img/reflection1.gif)
Uses of reflection of sound (echo)
(http://www.jfkscience.org/Physics/Notes/WAVES_files/image108.gif) (http://www.coml.org/edu/img/bottom-penetrating_sounders_01.gif)
-appreciate the way in which a wave can change direction as its speed changes
I think this is the explanation : relating it to the previous explanation, the phenomena can be called as refraction.
When a light wave passes form an optically denser median to a rarer medium or vise versa the speed as well as direction changes.
(http://lcogt.net/files/jbarton/glass%20block%20refraction.png)
In the picture : A ray of light enters from air into glass
- appreciate how reflection and refraction properties can be applied to understand the transmission of light down an optical fibre
Light can be trapped by total internal reflection inside a glass rod and 'piped' along a curve pat. A single, very thin glass fibre behaves in the same way.
See, you must know what is critical angle of a substance for the explanation. Critical angle is when the angle of refraction is 90*.
http://www.medrounds.org/optics-review/uploaded_images/Figure18-774908.jpg
In the picture : R2 shows the critical angle.
If this critical angle is exceeded, total internal reflection occurs. R3 in the picture shows total internal reflection.
Optic fibres use this principle to propagate light rays or any other electromagnetic radiation to long distances.
w0w.......that's tremendous work Vin :D
+ rep
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- appreciate how sound levels can be measured and appreciate the desirability of reducing noise levels yet recognise the problems involved in doing this
Alright, this part I think I have a slight idea but then I cannot be too sure and post inaccurate info. :/
What subjects is this, again? I've never ever learnt such stuff. :S
-understand that diffraction and the speed of light in glass, in relation to that in air, are some evidence for the wave nature of light
This simply means that light waves have the following properties : Diffraction and speed of light in air ( greater than in medium - glass/water etc.)
-appreciate how energy can be transferred from waves and how it is possible to be selective in making that transfer
Uhm, I'm not too sure about this. How about, when a disturbance is created, the particles transfer the energy one particle to another creating a wave. How it is possible to be selective in making that transfer - probably, take for example a loudspeaker, you can control the volume, so you're basically controlling the 'transfer of energy'. Light intensity - you can control it by using variable resistors.
I'm not sure though.
-appreciate that earthquakes involve the passage of waves through the Earth
I guess the Wikipedia link should help, cos I don't know anything significantly. :P
-understand that wave motion is a useful way of describing and explaining the behaviour of light and sound
Basically they mean the graphical representation (the pictures in my previous post) is useful? :/
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:D
Well, um, I hate to say this but, um, only emotions or symbols, or saying just "thanks" or "Thank you" are considered as spam and supposed to be deleted. Don't forget to add some text next time. ;) Can you modify your post please? (: