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GCSE core science 2014

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Reply 20
Original post by CJaymyers98
To get in to UCL you need to have exceptional talent, but i'm sure you do :-).

You seem very knowledgeable and interesting :-D What do you want to do at uni?

Also be prepared for a ridicolous exam, last january the chemistry exam was a beast, the grade boundaries an A* were 38, 29 for an A, 21 for a B.


You sure do, ucl is a top international university. I would like to do accounting.


Yes i heard about that exam, my best friend in year 11 was in tears after the exam. Apparently it was very difficult for a GCSE paper. My friend managed to scrape an A* with 39/60.
Thank you Nathalie for your help your a star!

I have uploaded an attachment on a checker booklet on everything I need to know. The p1 checker part higher is all the ones I personally need to know. I know this seems really big headed and too much to ask considering what you have already done for me would you mind answering all the checklist on only p1 part as it would really help with my revision.

If not I totally understand would just make my life easier!

pleas reply ASAP

thanks sara x
Reply 22
Original post by sarahussainxxx
Thank you Nathalie for your help your a star!

I have uploaded an attachment on a checker booklet on everything I need to know. The p1 checker part higher is all the ones I personally need to know. I know this seems really big headed and too much to ask considering what you have already done for me would you mind answering all the checklist on only p1 part as it would really help with my revision.

If not I totally understand would just make my life easier!

pleas reply ASAP

thanks sara x



can you give me an hour, sorry i will be as fast as i can.
Original post by NathalieGW
can you give me an hour, sorry i will be as fast as i can.


I cant belive your doing this your amazing! no one would ever do this for me I am entirely grateful thanks sooooo much xxx
Reply 24
Original post by sarahussainxxx
Thank you Nathalie for your help your a star!

I have uploaded an attachment on a checker booklet on everything I need to know. The p1 checker part higher is all the ones I personally need to know. I know this seems really big headed and too much to ask considering what you have already done for me would you mind answering all the checklist on only p1 part as it would really help with my revision.

If not I totally understand would just make my life easier!

pleas reply ASAP

thanks sara x



o Use specific heat capacity and specific latent heat equations, including a change of subject.

So specific heat capacity is the amount of energy needed to raise the temperture 1kg of a material by 1c.

Energy transferred= mass x specific heat capacity x change in temperature.

Mass = energy divided by (specific heat capacity times change in temperature) and to find shc or temperature you just rearange the formula. Energy is always the biggest value, so you always divide the energy the other non-subjects.


Explain why temperature does not change during a change of state.
tthe temperature stays the same during a change of state, melting or boiling, even though heat energy is still being absorbed. This is because energy is needed to break the bonds that hold the molecules together, as when a liquid turns in to a gas or a solid turns in to a liquid, the molecular bonds are broken so that the particles are further apart.

o Describe how energy is transferred by conduction, convection and radiation.


Conduction

Conduction is the transfer of energy in a solid. Particles in a solid are always vibrating, they are close together and move about a fixed position, this is because they have less activation and kinetic energy than liquids and gases.

When a solid is heated, the particles gain more kinetic energy and thus vibrate faster and more frequently, therefore colliding with one and another. It's the collisions that transfer energy from one particle to another.

Convection

Liquids and gases are fluids because they can be made to flow. The particles in these fluids can move from place to place. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. This convection.

Convection currents

When a fluid is heated, the particles gain more kinetic energy and thus move faster. As they move faster, they are taking up a larger volume and the fluid therefore expands as the particles are further apart. The warmer, less dense and more energetic fluid rises, whereas the denser, cooler and less energetic fluid falls to the bottom of the container. The container is the fixed area in which the fluid is contained.


Radiation (infrared also known as thermal radiation)

Heat can be transferred by infrared radiation. Unlike conduction and convection, which need particles, infrared radiation is a type of electromagnetic radiation that involves waves. Infra-red radiation can travel through a vacuum.

All objects emit and absorb infra-red radiation. If an object is cooler than it's surroundings it will absorb more infra-red radiation untill it's a the same temperature as it's surroundings. If an object is hotter than its surroundings, then it will emit more infra-red radiation untill it's a the same temperature as it's surroundings.

Shiny surfaces are good reflectors of infra-red radiation and bad absorbers and emitters. Whereas dark matt surfaces are bad reflectors, but good absorbers and emitters.

o Explain energy loss in a cavity wall and what measures can be taken to minimise it.


Cavity wall insulation fills the gap between the inside wall and bricks with a type of polymer foam. The foam has trapped air inside, the air cannot move so energy can't be transferred by convection. Since the particles need to move in order for convection to occur. The conduction is poor because both the plastic foam and trapped air are good insulators, meaning that they aren't good at conducting energy but are good at containing energy.




Explain
conduction, convection and radiation in terms of home and appliance design, and energy saving strategies.

Heat loss by conduction can be reduced by double glazing. The gap between the two panes of glass in a double glazed window is filled a vacuum or gas. The particles in a gas are very far apart, so it is very difficult for conduction to occur. There are no particles in a vacuum so it is impossible for conduction to occur.

I can't really think of anything else.
o Use the wave equation, including a change of subject and use of standard form.


The wave equation is wave speed = frequency times wavelength

This can be easily rearranged like the formula for energy.

Frequency= wavespeed divided by wavelength

wavelength = wavespeed divided by frequency.

Frequency is measured in hertz (hz)

Wavelength is measured in metres (m)

Wavespeed metres per second (m/s)

Standard form is 10 to the power of something e.g a million is 10 to the power of 6
as 10 times 10 times 10 times 10 times 10 times 10 = a million

it can be negative to e.g 0.001 = 10 to the power of negative of negative 3


Describe a diffraction pattern for waves, including the significance of the size of

Diffraction
Diffraction is the spreading of a wave as it passes through a gap or moves around an obstacle.

The larger, the wavelength of radiation, the more diffraction occurs. The most diffraction occurs when the size of the gap and wavelength of radiation are a similar size.

Describe and explain the limiting effects of diffraction on telescopes and optical microscopes.

Diffraction reduces the quality of images seen in microscopes and telescopes. It can cause rings or spikes around the image of the object being viewed. I think that's what it means.



o Explain the advantages and disadvantages of different communication systems.



Ok so i will start with microwaves.

Mobile phones communicate with their base stations using low-intensity microwave radiation. The microwaves used in mobile phones have to travel further, so have longer wavelengths and are less penetrating than the microwaves used in microwave ovens, this is an advantage. A disadvantage in using microwaves for mobiles phones is that, they can penetrate body tissues to a depth of a few centimetres. The body tissues absorb and this can cause a small amount of heating, about 0.1°C. AS the cells are heated, they denature, this can therefore cause cancer and a loss in water due to the heat.

Microwaves cannot diffract much, as they have shorter wave-lengths can radio-waves and therefore signals can be lost easily. In adverse weather conditions signals can scatter.

Radiowaves.

radio waves have a large wavelength so they experience less interference and can travel over large distances. However, since they do not have a high frequency, they cannot transmit as much data.


o Describe why morse code is a digital signal.




Morse code can be used to transmit signals in many different ways, including visible light, radio waves and electrical pulses. Why is a digital signal? well because it can be replicated by digital processes.
Sending information using electrical pulses requires wires, unlike visible light and radio waves, which are wireless. The use of visible light needs the transmitter and receiver to be in the line of sight
o Describe applications of Total Internal Reflection in fibre optics.


An optical fibre is a thin tube made out of high quality glass. The light undergoes constant total internal reflection and the advantage is that the light can travel travel in pulses at very high speeds and it works even if the tube is bent.

Optical fibres can carry more information than an ordinary cable of the same thickness. The signals in optical fibres do not weaken as much over long distances as the signals in ordinary cables.

Total

o Explain why lasers produce an intense, coherent beam of light.


Laser is an acronym which stands for Light Amplification by Stimulated Emission of Radiation, i believe.
The light waves have a low divergence, which means they don't spread out much, they are also coherent, which means that they are in the same frequency and in the same phase with each other.


o Explain how a laser beam is used in a CD player.



The shiny surface of a CD contains pits, the pits code for a digital signal. The laser light is applied on the CD surface, and the change in reflection provides information from the digital signal.



o Explain how microwaves and infrared transfer energy to materials.

A microwave oven uses microwaves to transfer energy to the food. Microwave radiation is absorbed by water particles in the food , both on the surface and up to about 1 cm deep into the food. These particles gain more kinetic energy and the rest of the food (inner layers) is heated by conduction.

A normal oven uses infra-red radiation to heat food. The outer layer particles of the food are heated and gain more kinetic energy, the outer layer particles transfer energy to the inner layer particles by conduction. I
nfrared radiation has a higher frequency than microwaves. It can transfer enough energy to break chemical bonds. Microwaves cannot and this is why food burns when you overheat it.







(edited 9 years ago)
Reply 25
Second part, i couldn't post more. I should be another 20 minutes.

Took longer than expected as i was busy.

You're exam board is ocr right? So i'm on a different exam board and the syllabus is different. Some of this from general knowledge. This thread is about core science so i'm willing to help with any enquires linked to the course XD


Explain how microwave and infrared radiation transfers energy to materials.

Microwaves penetrate up to 1cm into food. Microwaves penetrate through glass and plastic but are reflected by shiny metal surfaces. Special glass in a microwave oven door reflects the microwaves.

Microwaves cook food bu microwave radiation. The water and fat molecules in the outer layers of the food absorb the microwave radiation and vibrate more, energy is subsequently transferred to the inner layers of the food conduction.

Normal ovens cook food bu infrared radiation. Energy is absorbed by the surface food particles and is transferred to the inner layers by conduction as the particles gain more kinetic energy.

Describe how energy associated with microwaves and infrared depends on their frequency.

High frequency waves transfer more energy .

Recall the energy of microwaves and infrared to their potential dangers.

Microwaves cannot be seen as their wavelengths are too long. They burn tissue as the water molecules absorb the radiation, this can lead to cancer. They have shorter wavelengths than the microwaves used for mobile phones and thus cause more damage.

Infrared radiation causes to skin.

Explain how microwave signal loss happens.


In the use of microwaves in communication, the transmitter and receiver must be in line of sight.

Microwaves do not show much diffraction, so sometimes cannot diffract around buildings. The natural curvature of the earth limits the line of sight and adverse weather cinditions scatter signals.

Explain how signal loss problems can be reduced

Signal loss can reduced situating aerials on top of high buildings. Satelites are in line of sight as there are no obstructions in space. Large aerials can handle thousands of signals at once.


Explain how a remote control


Pressing a button on a remote control
A coded signal is sent to a light emitting diode (LED) at the front of the remote. The signal includes a start command, the instruction command, a device code and a stop command

The LED then transmitts a series of pulses which are received and decoded by the device, so that it can complete a function. Like changing volume or channel.

Describe the advantages of digital signals

Digital signaks can use multiplexing, which enables large numbers of signals to be transmitted simultaneously.

Inteference isn't apparent on digital signals, as digital signals only have two values.

Describe the advantages of optical fibres

Optical fibres allow data to be transmitted faster than microwaved and radiowaves, visible light has a higher frequency, optical fibres still work when bent, whereas normal wires don't.
(edited 9 years ago)
Reply 26
Final bit..

Explain the dependencied involved in long-distance communication.

The transmitter and receiver must be in line of sight, aerials have to be on top of high buildings.

Recall how refraction and reflection in the atmosphere is similar to total intetnsl reflection.

Radiowaves are reflected in the ionosphere. The ionosphere is an electrically charged layer of the atmosphere which is ionised by solar radiation.Radiowaves behave like light in an optical fibre and undergo total internal reflection.

Explain how diffraction and refraction affects communication.

Radiowaves and microwaves are refracted in the atmosphere, some energy is lossed and this slows down the speed of signals.

Diffraction by transmission dishes results in communication loss.

Explain the advantages and disadvantages of digital radio in terms of interference.

Digital signals eliminate interference.


Describe how seismic waves can provide evidence for the structure of the earth.

P waves can pass through solids and liquids, they are refracted by the core. The paths taken by p waves allows scientists to calculate the size of the core.

S waves can only pass through solids, so they are not detected on the othet sude of the earth to an earthquake and this proves that the earths core is liquid.

Describe how the ozone layer pretects


The ozone layer helps filter out ultraviolent radiation.

Describe the effects of environmental pollution of cfcs'.

Cfcs' destroy ozons and thus reduce the thickness of the ozone layer, this means that more ozone reaches the lower atmosphere, earth and effects hunan skill. In some cases this can lead to cancer.

Explain how the discovery of ozone has changed behaviour.


People use less aerosoles as they emit cfc gases, which deplete ozone i guess.

Also refraction is the change in speed and direction of a wave as it changes medium. As a wave enters a denser medium its speed decreases and it bends towards the normal, as a wave enters a denser medium its speed increases and it bends away from the normal.

Are you sure you know everything in Chemistry?.
I'm the chemist here if anyone needs help in chemistry :-D
Original post by NathalieGW
You sure do, ucl is a top international university. I would like to do accounting.


Yes i heard about that exam, my best friend in year 11 was in tears after the exam. Apparently it was very difficult for a GCSE paper. My friend managed to scrape an A* with 39/60.


Judging by your replies, you're looking very promising and you can clearly think outside of the box, so you haven't got anything to worry about really :-)
Reply 29
Original post by CJaymyers98
Judging by your replies, you're looking very promising and you can clearly think outside of the box, so you haven't got anything to worry about really :-)



Honestly? science isn't even my thing. That's why i'm doing double award.
My favourite subjects are Maths, Geography, English and P.E.
Original post by NathalieGW
Reflex actions are instaneous and prevent dangerous situations, whereas normal responses are voluntary?.

Reflex actions aren't coordinated by the brain, just the spinal cord.

Cells? I don't think that's in the spec. Do you mean the structure and properties of cells?. Animal and plant cells, which we learnt in year 9?.

Weight is gravity times mass i think. Forces are measured in newtons. This isn't in the aqa core science specification, i just know from general knowledge.

I'm pretty fluent in Physics, i know all the formulas by heart, i'm confident with waves and their properties, energy transfers and sources, national grid etc.

Maths is my best subject, so i'm naturally better at chemistry and physics.

When are your additional science exams?.

Thanks for the tips :-).


Yeah you got it reflexes are involetary, I forgot what else you need.0
In physics you don't actually need to learn the equations off by heart but if you know them even better.
You got weight right mass x gravitational field strength =weight.
Yeah the cells is just the structures of them eg.cell membrane, nucleus etc

You sound like your good at physics, what are you thinking about taking for a level?
I took triple science and both biology exams were today as well as my geography exam and all I can say is to revise EVERYTHING because the paper was really hard, i don't know if its because I didn't revise enough but from the look of twitter it looks like everybody found it quite hard. Even in geography we had to learn like 17 case studies and a singular one came up!:frown: not fun AQA
Reply 31
Original post by vish.handa
Yeah you got it reflexes are involetary, I forgot what else you need.0
In physics you don't actually need to learn the equations off by heart but if you know them even better.
You got weight right mass x gravitational field strength =weight.
Yeah the cells is just the structures of them eg.cell membrane, nucleus etc

You sound like your good at physics, what are you thinking about taking for a level?
I took triple science and both biology exams were today as well as my geography exam and all I can say is to revise EVERYTHING because the paper was really hard, i don't know if its because I didn't revise enough but from the look of twitter it looks like everybody found it quite hard. Even in geography we had to learn like 17 case studies and a singular one came up!:frown: not fun AQA


AQA is said to be the hardest examboard. Pretty much all my subjects are AQA apart from Computer Science.

I heard about those exams, everyone who took them is saying they were unfair.

I've been doing some long answer questions in biology, it's important to get those six valueble marks, there's about two of them in each exam.

I've also been looking at the terms used, so that i can underline specifically what each question is asking. E.g whether the question is asking you to explain, describe or evaluate etc.
My choices are Geography, Maths, Further Maths and either Physics or Chemistry. I think i will base it on Which science exam i get the highest mark in.

What are your choices and do you have an idea of what you want to do at uni?
(edited 9 years ago)
Original post by NathalieGW
AQA is said to be the hardest examboard. Pretty much all my subjects are AQA apart from Computer Science.

I heard about those exams, everyone who took them is saying they were unfair.

I've been doing some long answer questions in biology, it's important to get those six valueble marks, there's about two of them in each exam.

I've also been looking at the terms used, so that i can underline specifically what each question is asking. E.g whether the question is asking you to explain, describe or evaluate etc.
My choices are Geography, Maths, Further Maths and either Physics or Chemistry. I think i will base it on Which science exam i get the highest mark in.

What are your choices and do you have an idea of what you want to do at uni?


Yeah we got told to learn all about the key words, i only really learned the basics. For the geography there were some stupid questions so i'm relying on human geography which is never a good thing. What topics in geography are you doing? The six markers are my least favorite because its sometimes not even clear cut, its the examiners interpretation.
Those are good choices I enjoy all them subjects but i am in 2nd set for maths atm and i'm doing Maths, physics, chemistry and business studies. Uni wise I want to do physics but if all my science and maths fails I left business as a back up. You seem suited for both chemistry and physics so whichever floats your boat really.At the end of the day it's what you enjoy because that's what you will work harder for. Also you have the unit 2 topics to learn. Good ol' neutralization reactions :colone: . To be honest you sound like you could have dealt with triple but did it count as one of your choices? For use we picked two free subjects one humanity and one language:angry::angry::angry: as well as a choice of triple or double. Wbu?
Reply 33
Original post by vish.handa
Yeah we got told to learn all about the key words, i only really learned the basics. For the geography there were some stupid questions so i'm relying on human geography which is never a good thing. What topics in geography are you doing? The six markers are my least favorite because its sometimes not even clear cut, its the examiners interpretation.
Those are good choices I enjoy all them subjects but i am in 2nd set for maths atm and i'm doing Maths, physics, chemistry and business studies. Uni wise I want to do physics but if all my science and maths fails I left business as a back up. You seem suited for both chemistry and physics so whichever floats your boat really.At the end of the day it's what you enjoy because that's what you will work harder for. Also you have the unit 2 topics to learn. Good ol' neutralization reactions :colone: . To be honest you sound like you could have dealt with triple but did it count as one of your choices? For use we picked two free subjects one humanity and one language:angry::angry::angry: as well as a choice of triple or double. Wbu?

Which are you better at, Physical or Human Geography?.

We are currently doing Weather in Physical, which is personally my favourite topic, a long with weathering. I'm also looking forward to eco-systems. Ecology fascinates me :-D.

In Human Geography we are on farming. How sedentary farning is when farming is based in one location, normaduc farming is when farmers change location and its more common in LEDCs, stuff like that.

Urban population was far more interesting!. I would say my favourite topic in Human Geography is Globalization, economics is fun.

As i was top set science in year 9, i was able to choose whether to do double or tripple. I'm stronger in Maths and Geography and i didn't fancy having 9 science lessons a week, so chose the double award.

Additional Science looks fun. I'm very good at balancing equations. (The biology looks difficult).

I would like to do Accounting at LSE or UCL.
Original post by NathalieGW
Which are you better at, Physical or Human Geography?.

We are currently doing Weather in Physical, which is personally my favourite topic, a long with weathering. I'm also looking forward to eco-systems. Ecology fascinates me :-D.

In Human Geography we are on farming. How sedentary farning is when farming is based in one location, normaduc farming is when farmers change location and its more common in LEDCs, stuff like that.

Urban population was far more interesting!. I would say my favourite topic in Human Geography is Globalization, economics is fun.

As i was top set science in year 9, i was able to choose whether to do double or tripple. I'm stronger in Maths and Geography and i didn't fancy having 9 science lessons a week, so chose the double award.

Additional Science looks fun. I'm very good at balancing equations. (The biology looks difficult).

I would like to do Accounting at LSE or UCL.


Personally I think I'm better at physical because it actually interests me whereas human bores me a bit. We do glaciation coasts and tectonic plates
For human rural/farming population and tourism but its just rural environments to be honest, they literally make me want to give up :smile:
Sounds good at least you have plans on what you'd like to do! To be honest I actually love science so number of lessons didn't really bother me but I can't revise my chemistry Atm I keep getting distracted :no: if you did triple you would have to do titrations, but even in additional you have quite a bit of maths with empirical formula and moles to look forward too!
Reply 35
Original post by vish.handa
Personally I think I'm better at physical because it actually interests me whereas human bores me a bit. We do glaciation coasts and tectonic plates
For human rural/farming population and tourism but its just rural environments to be honest, they literally make me want to give up :smile:
Sounds good at least you have plans on what you'd like to do! To be honest I actually love science so number of lessons didn't really bother me but I can't revise my chemistry Atm I keep getting distracted :no: if you did triple you would have to do titrations, but even in additional you have quite a bit of maths with empirical formula and moles to look forward too!


I just don't go online until i'm satisfied with my revision or if i really need an online source e.g specifications or to print of exam papers.

Are you sitting the Chemistry exam tomorrow? If so then good luck.

With maths are you doing the linear route (calculator paper and non-calculator) or the modular route?.


My school do the modular route (unit 1 at the end of year 10, unit 2 and 3 at the end of year 11). I'm sitting unit 1 this year.
In A-level maths you sit three maths exams per year and with further it's altogether six exams per year That's mental right?.
Original post by NathalieGW
I just don't go online until i'm satisfied with my revision or if i really need an online source e.g specifications or to print of exam papers.

Are you sitting the Chemistry exam tomorrow? If so then good luck.

With maths are you doing the linear route (calculator paper and non-calculator) or the modular route?.


My school do the modular route (unit 1 at the end of year 10, unit 2 and 3 at the end of year 11). I'm sitting unit 1 this year.
In A-level maths you sit three maths exams per year and with further it's altogether six exams per year That's mental right?.


Yeah I should probably stay off the internet while revising:sigh: but I don't take breaks except in the room because otherwise I lose the mood
Yes I'm sitting it tomorrow and thank you :biggrin:
We d linear so calc and non calc but our exam isn't till June so I've got plenty of time for that
A level maths looks crazy in itself let alone further maths and they get like 2 a4 pages for one question :/...
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I think I've got most of core down, so feel free to ask if you need any help (it has been a while since I last looked at it though :colondollar:)

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Reply 38
Original post by vish.handa
Yeah I should probably stay off the internet while revising:sigh: but I don't take breaks except in the room because otherwise I lose the mood
Yes I'm sitting it tomorrow and thank you :biggrin:
We d linear so calc and non calc but our exam isn't till June so I've got plenty of time for that
A level maths looks crazy in itself let alone further maths and they get like 2 a4 pages for one question :/...
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What is the carbon chemistry like in Additional science?.
It sure does, nothing wrong with challenging yourself past your boundaries though :wink:. I have done a bit of self-set work in C1, which isn't a massive step up, it's C2 when you get thrown in the deep end.

I have a two hour IGCSE french exam coming up, i'm really going to struggle with that.

Finding the motivation to revise can be difficult, i feel your pain :cool:.
Reply 39
Original post by majmuh24
I think I've got most of core down, so feel free to ask if you need any help (it has been a while since I last looked at it though :colondollar:)

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Which exam board?

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